Updated on 2026/03/05

写真a

 
KITAMOTO YOSHITAKA
 
Organization
School of Materials and Chemical Technology Professor
Title
Professor
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Degree

  • Master of Engineering ( Tokyo Institute of Technology )

  • Doctor of Engineering ( Tokyo Institute of Technology )

Research Areas

  • Nanotechnology/Materials / Nanomaterials

Education

  • Tokyo Institute of Technology   Science of Engineering

    - 1988

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    Country: Japan

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  • Tokyo Institute of Technology   School of Engineering   Department of Electrical and Electronic Engineering

    - 1986

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    Country: Japan

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Research History

  • Institute of Science Tokyo

    2024.10

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  • Institute of Science Tokyo   Professor

    2024.10

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    Country:Japan

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  • Tokyo Institute of Technology   Professor

    2013.12 - 2024.9

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    Country:Japan

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  • Tokyo Institute of Technology

    2000.4 - 2013.11

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  • Tokyo Institute of Technology

    1995.7 - 2000.3

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  • (株)レイケム   主任

    1992.8 - 1995.6

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  • 日本ディジタルイクイップメント(株)   研究員

    1988.4 - 1992.7

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Professional Memberships

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Committee Memberships

  • 粉体粉末冶金協会   副会長  

    2024.5   

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  • 粉体粉末冶金協会   理事  

    2020.5   

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Papers

  • Polydopamine-Functionalized Magnetoliposomes as Magnetic Probes for Lectin–Glycan Interaction Analysis through Brownian Relaxation Reviewed

    Adira N. Ryofi, Kyohei Okubo, Akito Nunome, Tsung-Che Chang, Katsunori Tanaka, Yoshitaka Kitamoto

    ACS Applied Materials & Interfaces   17 ( 43 )   59094 - 59107   2025.10

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society (ACS)  

    DOI: 10.1021/acsami.5c12462

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  • Magnetically Hydrodynamic Behavior of Magnetoliposomes Designed for Liquid-Based Biomolecular Sensing Reviewed

    Adira Nofeadri Ryofi, Kyohei Okubo, Yoshitaka Kitamoto

    Journal of the Japan Society of Powder and Powder Metallurgy   72 ( Supplement )   S689 - S696   2025.3

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Japan Society of Powder and Powder Metallurgy  

    DOI: 10.2497/jjspm.15e-t16-11

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  • Enhancement of acoustic cavitation using chitosan nanoparticle-shelled composites Reviewed

    Xue Xie, Yuta Kurashina, Kyohei Okubo, Hiroyuki WADA, Yoshitaka KITAMOTO

    Japanese Journal of Applied Physics   64 ( 2 )   025002   2025.2

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:IOP Publishing  

    Abstract

    Ultrasound cavitation finds diverse applications across biomedical engineering, chemical processes, and industrial systems. Its effects significantly influence the performance of ultrasound imaging and targeted drug delivery. Although microbubbles have been found to enhance cavitation activity, their effect is practically insufficient. To enhance cavitation activity, we introduce a composite structure utilizing chitosan nanoparticles as a stabilizing shell. The relationship between chitosan nanoparticle size and the initial concentrations of chitosan and sodium tripolyphosphate linker is systematically analyzed. The cavitation effect associated with these chitosan nanoparticle-shelled composites is assessed using iodide dosimetry under ultrasonic irradiation at 20 kHz. Composites encapsulated by a positively charged chitosan nanoparticle shell, measuring 23 nm in size, demonstrate significant improvements in hydroxyl radical generation compared to untreated samples, indicating enhanced acoustic cavitation. These findings highlight the potential of combining chitosan nanoparticles with microbubbles for versatile applications ranging from ultrasound imaging to drug delivery.

    DOI: 10.35848/1347-4065/adb190

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    Other Link: https://iopscience.iop.org/article/10.35848/1347-4065/adb190/pdf

  • Finite Element-Based Simulation Model for Brownian Relaxation Behavior of Magnetic Nanoparticle Clusters for Biosensing Applications

    Shaomeng Yang, Kyohei Okubo, Yoshitaka Kitamoto

    2025

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    Publisher:Elsevier BV  

    DOI: 10.2139/ssrn.5102423

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  • Effect of interparticle and inter-cluster dipole–dipole interactions on dynamic behavior of superparamagnetic iron oxide nanoparticles modified with citric acid Reviewed

    W. Muliawan, K. Okubo, Y. Kitamoto

    Journal of Applied Physics   136 ( 7 )   073903   2024.8

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:AIP Publishing  

    This paper describes the hydrodynamic behavior of superparamagnetic iron oxide nanoparticles modified with citric acid (CA-SPIONs) in suspension under alternating current magnetic fields given interparticle and inter-cluster dipole–dipole interactions. The cluster size of the CA-SPIONs is modulated to control interparticle interactions, and the ionic concentration of the CA-SPION suspension is varied to control inter-cluster interactions. Dynamic magnetic susceptibility (DMS) measurements of the CA-SPION suspensions under alternating current magnetic fields indicate that the interparticle interaction by clustering and the inter-cluster interaction by increasing the ionic concentration cause frequency spectra modulation, such as their broadening in the low-frequency region and a decrease in the Brownian relaxation frequency. The experimentally obtained DMS spectra differ from the spectra numerically calculated from the hydrodynamic size distribution of CA-SPIONs using the Debye relaxation model without considering the magnetic interactions; the differences are attributed to the interparticle and inter-cluster dipole–dipole interactions. These insights contribute to a deeper understanding of dynamics of superparamagnetic iron oxide nanoparticles and facilitate nanoparticle parameter optimization for tailored applications in the biomedical field, particularly for their efficacy and precision in liquid-phase biosensing and imaging.

    DOI: 10.1063/5.0220689

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  • Magento-fluorescent uniform sub-micron up-conversion capsules for potential simultaneous MRI/PL imaging and drug delivery capabilities Reviewed

    Syed Mujtaba ul Hassan, Tanzeela Anis, Yoshitaka Kitamoto

    Inorganic Chemistry Communications   167   112676 - 112676   2024.6

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.inoche.2024.112676

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  • Efficient delivery of anticancer drugs using functionalized-Ag-decorated Fe3O4@SiO2 nanocarrier with folic acid and β-cyclodextrin Reviewed

    Yoga Romdoni, Eka Sunarwidhi Prasedya, Grandprix T.M. Kadja, Yoshitaka Kitamoto, Munawar Khalil

    Biochimica et Biophysica Acta (BBA) - General Subjects   1868 ( 8 )   130643 - 130643   2024.5

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.bbagen.2024.130643

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  • Estimation of biomolecule amount by analyzing magnetic nanoparticle cluster distributions from alternating current magnetization spectra for magnetic biosensing Reviewed

    Ye Chen, Kyohei Okubo, Konstantinos Slavakis, Yoshitaka Kitamoto

    Journal of Magnetism and Magnetic Materials   588   171387   2023.10

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.jmmm.2023.171387

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  • Acoustic-responsive carbon dioxide-loaded liposomes for efficient drug release Reviewed

    Yasuhiko Orita, Susumu Shimanuki, Satoshi Okada, Kentaro Nakamura, Hiroyuki Nakamura, Yoshitaka Kitamoto, Yusuke Shimoyama, Yuta Kurashina

    Ultrasonics Sonochemistry   94   106326 - 106326   2023.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.ultsonch.2023.106326

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  • Synthesis and characterization of pH-responsive ferrogels comprising sulfamethazine-based polymer and magnetic nanoparticles for sensing ammonia gas Reviewed

    Ye Chen, Masataka Abe, Ikuyoshi Tomita, Yuta Kurashina, Yoshitaka Kitamoto

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   565   170201   2022.11

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.jmmm.2022.170201

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  • Synthesis of multifunctional Fe3O4@SiO2-Ag nanocomposite for antibacterial and anticancer drug delivery Reviewed

    Yoga Romdoni, Grandprix T.M. Kadja, Yoshitaka Kitamoto, Munawar Khalil

    Applied Surface Science   610   155610   2022.11

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.apsusc.2022.155610

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  • Preparation of CeO2 nanoparticles by laser ablation in liquid method and its UV absorption properties Reviewed

    Mengqi Shi, Yoshitaka Kitamoto, Masahiko Hara, Hiroyuki Wada

    Appl. Phys. A   128   968   2022.10

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1007/s00339-022-06086-8

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  • Effect of irradiation time on characteristics of Gd2O3:Er,Yb NPs by laser ablation in liquid Reviewed

    Yuri Tei, Yoshitaka Kitamoto, Masahiko Hara, Hiroyuki Wada

    Applied Physics A   128   789   2022.8

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    DOI: 10.1007/s00339-022-05901-6

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    Other Link: https://link.springer.com/article/10.1007/s00339-022-05901-6/fulltext.html

  • Transdermal delivery of bFGF with sonophoresis facilitated by chitosan nanocarriers Reviewed

    Xue Xie, Yuta Kurashina, Makoto Matsui, Takahiro Nomoto, Munenari Itoh, Hirotaka J. Okano, Kentaro Nakamura, Nobuhiro Nishiyama, Yoshitaka Kitamoto

    Journal of Drug Delivery Science and Technology   75   103675 - 103675   2022.8

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    Authorship:Last author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.jddst.2022.103675

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  • Levilactobacillus brevis surface layer protein B promotes liposome targeting to antigen-presenting cells in Peyer’s patches Reviewed

    Zheng Lin Tan, Kazuhiko Miyanaga, Yoshitaka Kitamoto, Naoyuki Yamamoto

    International Journal of Pharmaceutics   622   121896 - 121896   2022.6

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    DOI: 10.1016/j.ijpharm.2022.121896

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  • Optical properties of copper naphthalocyanine nanoparticles prepared by laser ablation in liquid Reviewed

    Keita Omura, Yoshitaka Kitamoto, Masahiko Hara, Hiroyuki Wada

    Japanese Journal of Applied Physics   61 ( 4 )   042001 - 042001   2022.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:IOP Publishing  

    Abstract

    Copper naphthalocyanine nanoparticles were successfully prepared by laser ablation in liquid. Micron-size copper naphthalocyanine powders were used as the raw material in water and were irradiated with a laser beam (Nd:YAG, SHG) to obtain nanoparticles. Nanoparticles were examined by scanning electron microscopy, dynamic light scattering, a spectrophotometer, and Raman spectroscopy. Even in the case of irradiation at low laser fluence and for short irradiation times, nanoparticles were obtained owing to the comparatively low threshold of laser ablation. Laser irradiation changed the crystal structure, but the composition of the nanoparticles was not altered by laser irradiation. The dispersion stability of nanoparticle solution was very high, and absorbance of the solution was almost constant without precipitation. The conversion rate from raw material to nanoparticle was 85.5%. The Grüneisen coefficient for the copper naphthalocyanine nanoparticles was also high; therefore, the produced copper naphthalocyanine nanoparticles were suitable as a contrast agent for photoacoustic imaging.

    DOI: 10.35848/1347-4065/ac4e30

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    Other Link: https://iopscience.iop.org/article/10.35848/1347-4065/ac4e30/pdf

  • Quantitative Analysis of Acoustic Pressure for Sonophoresis and Its Effect on Transdermal Penetration Reviewed

    Yuta Kurashina, Risa Asano, Makoto Matsui, Takahiro Nomoto, Keita Ando, Kentaro Nakamura, Nobuhiro Nishiyama, Yoshitaka Kitamoto

    Ultrasound in Medicine & Biology   48 ( 5 )   933 - 944   2022.3

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    Authorship:Last author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.ultrasmedbio.2022.01.021

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  • Bifunctional folic-conjugated aspartic-modified Fe3O4 nanocarriers for efficient targeted anticancer drug delivery Reviewed

    Munawar Khalil, Ely Arina Haq, Astari Dwiranti, Eka Sunarwidhi Prasedya, Yoshitaka Kitamoto

    RSC Advances   12 ( 8 )   4961 - 4971   2022.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Royal Society of Chemistry (RSC)  

    Aspartic acid was used as an anchoring molecule for the conjugation of folic acid and doxorubicin to Fe3O4 nanoparticles. The as-prepared bifunctional folic-conjugated aspartic-modified Fe3O4 nanocarrier was shown to be as an efficient targeted anticancer drug delivery.

    DOI: 10.1039/d1ra08776b

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  • Preparation of Gd2O3:Er,Yb Nanoparticles by Laser Ablation in Liquid and Their Optical Properties for Biomedical Application Reviewed

    Yuri Tei, Haohao Wang, Yoshitaka Kitamoto, Masahiko Hara, Hiroyuki Wada

    Journal of Laser Micro/Nanoengineering   16 ( 2 )   115 - 120   2021.10

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    Publishing type:Research paper (scientific journal)   Publisher:Japan Laser Processing Society  

    DOI: 10.2961/jlmn.2021.02.2007

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  • Preparation Copper Sulfide Nanoparticles by Laser Ablation in Liquid and Optical Properties Reviewed

    Kazuki ISODA, Ryuga YANAGIHARA, Yoshitaka KITAMOTO, Masahiko HARA, Hiroyuki WADA

    IEICE Transactions on Electronics   E104.C ( 8 )   390 - 393   2021.8

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Institute of Electronics, Information and Communications Engineers (IEICE)  

    DOI: 10.1587/transele.2020ecs6027

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  • Magnetic Properties and Particle Flowability of Neodymium Magnetic Granules Reviewed

    Yasushi Enokido, Fumitaka Baba, Yoshitaka Kitamoto

    MATERIALS TRANSACTIONS   62 ( 7 )   988 - 994   2021.6

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    Authorship:Last author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Japan Institute of Metals  

    DOI: 10.2320/matertrans.mt-m2021017

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  • The Lack of SNARE Protein Homolog Syn8 Influences Biofilm Formation of Candida glabrata Reviewed

    Xinyue Chen, Shun Iwatani, Toshitaka Kitamoto, Hiroji Chibana, Susumu Kajiwara

    Frontiers in Cell and Developmental Biology   9   2021.2

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    Biofilm formation of Candida species is considered to be a pathogenic factor of host infection. Since biofilm formation of Candida glabrata has not been as well studied as that of Candida albicans, we performed genetic screening of C. glabrata, and three candidate genes associated with biofilm formation were identified. Candida glabrata SYN8 (CAGL0H06325g) was selected as the most induced gene in biofilm cells for further research. Our results indicated that the syn8Δ mutant was defective not only in biofilm metabolic activity but also in biofilm morphological structure and biomass. Deletion of SYN8 seemed to have no effect on extracellular matrix production, but it led to a notable decrease in adhesion ability during biofilm formation, which may be linked to the repression of two adhesin genes, EPA10 and EPA22. Furthermore, hypersensitivity to hygromycin B and various ions in addition to the abnormal vacuolar morphology in the syn8Δ mutant suggested that active vacuolar function is required for biofilm formation of C. glabrata. These findings enhance our understanding of biofilm formation in this fungus and provide information for the development of future clinical treatments.

    DOI: 10.3389/fcell.2021.607188

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  • Preparation of Cu2ZnSnS4nanoparticles by laser ablation in liquid and characterization

    Li Kun, Yoshitaka Kitamoto, Masahiko Hara, Hiroyuki Wada

    Journal of Laser Applications   33 ( 1 )   2021.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Laser Institute of America  

    DOI: 10.2351/7.0000299

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  • Effect of grain-boundary phases in Y- and Ce-substituted R<inf>2</inf>Fe<inf>14</inf>B sintered magnets Reviewed

    Yasushi Enokido, Atsushi Koda, Yuji Umeda, Daisuke Tanaka, Yoshitaka Kitamoto

    Journal of Magnetism and Magnetic Materials   517   167406   2020.9

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    Authorship:Last author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.jmmm.2020.167406

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  • High-Throughput Screening Method for Thin-Film R<inf>2</inf>Fe<inf>14</inf>B Magnet Reviewed

    Yasushi Enokido, Ryuji Hashimoto, Tomoko Kitamura, Kenichi Suzuki, Kyung Ku Choi, Yoshitaka Kitamoto

    IEEE Transactions on Magnetics   56 ( 4 )   2020.4

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    Authorship:Last author   Publishing type:Research paper (scientific journal)  

    DOI: 10.1109/TMAG.2019.2962015

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  • Distributive Activation Volumes of Magnetically Interacting Nanostructures Reviewed

    Suko Bagus Trisnanto, Yoshitaka Kitamoto

    Journal of Physical Chemistry C   123   23732 - 23737   2019.9

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    DOI: 10.1021/acs.jpcc.9b05584

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  • Effect of Ionic Concentration on Dynamic Magnetic Susceptibility of Iron Oxide Nanoparticles Embedded in Chitosan Hydrogel Matrix Reviewed

    M. E. Villamin, Y. Kitamoto

    Transaction of the Magnetics Society of Japan Special Issues   3 ( 1 )   113 - 119   2019.5

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  • Influence of pH on Dynamic Magnetic Susceptibility of Iron-Oxide Nanoparticles in a Chitosan Hydrogel Matrix Reviewed

    Maria Emma Villamin, Yoshitaka Kitamoto

    IEEE Transactions on Magnetics   55 ( 2 )   2019.2

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    Publishing type:Research paper (scientific journal)  

    DOI: 10.1109/TMAG.2018.2869828

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  • Facile synthesis and AC characterization of chitosan and iron oxide nanoparticles magnetic beads

    Maria Emma Villamin, Yoshitaka Kitamoto

    AIP Conference Proceedings   2067   2019.1

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:American Institute of Physics Inc.  

    DOI: 10.1063/1.5089449

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  • A study on lattice matching method by CoRu layer between CoCrPtB magnetic layer and CrTi-(Mo, W) alloy underlayer Reviewed

    Yoshibumi Matsuda, Koji Sakamoto, Yotsuo Yahisa, Yuzuru Hosoe, H. Hosoda, Y. Kitamoto

    Journal of Magnetism and Magnetic Materials   469   545 - 549   2019.1

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    Authorship:Last author, Corresponding author   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.jmmm.2018.09.001

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  • Fabrication of porous FePt microcapsules for immunosensing techniques Reviewed

    Kumiko Miyajima, Yuki Miwa, Yoshitaka Kitamoto

    Colloids and Surfaces B: Biointerfaces   173   407 - 411   2019.1

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    Authorship:Last author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.colsurfb.2018.10.004

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  • ナノメディシンデバイスのための磁性・金複合ナノシェル Reviewed

    北本 仁孝, 張 茹芝

    粉体および粉末冶金   Vol. 65 ( No. 9 )   pp. 595 - 600   2018.9

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  • Refined Structural Analysis of Connected Platinum-Iron Nanoparticle Catalysts with Enhanced Oxygen Reduction Activity Reviewed

    Hidenori Kuroki, Takanori Tamaki, Masashi Matsumoto, Masazumi Arao, Yohei Takahashi, Hideto Imai, Yoshitaka Kitamoto, Takeo Yamaguchi

    ACS Applied Energy Materials   1 ( 2 )   324 - 330   2018.2

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    Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acsaem.7b00295

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  • Influence of behaviors of magnetic particles in ferrofluids under alternating magnetic fields on harmonic responses Reviewed

    Shoya Oda, Suko Bagus Trisnanto, Yoshitaka Kitamoto

    Japanese Journal of Applied Physics   57 ( 2 )   02CB17   2018.2

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    Publishing type:Research paper (international conference proceedings)  

    DOI: 10.7567/JJAP.57.02CB17

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  • Dipolar magnetism and electrostatic repulsion of colloidal interacting nanoparticle system Reviewed

    Suko Bagus Trisnanto, Kazuki Yasuda, Yoshitaka Kitamoto

    Japanese Journal of Applied Physics   57 ( 2 )   02CC06   2018.2

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    Publishing type:Research paper (international conference proceedings)  

    DOI: 10.7567/JJAP.57.02CC06

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  • NIR-responsive upconversion nanoparticles/anatase TiO<inf>2</inf> composite aerogel Reviewed

    Fu Chih Li, Hiroyuki Wada, Yoshitaka Kitamoto

    Japanese Journal of Applied Physics   57 ( 2 )   02CC03   2018.2

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    Publishing type:Research paper (international conference proceedings)  

    DOI: 10.7567/JJAP.57.02CC03

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  • Fabrication of Fe<inf>3</inf>O<inf>4</inf> nanorods designed for liquid-phase magnetic biosensing Reviewed

    Kazuki Yasuda, Yoshitaka Kitamoto

    AIP Conference Proceedings   1929   020009   2018.1

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    Publishing type:Research paper (international conference proceedings)  

    DOI: 10.1063/1.5021922

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  • Fabrication of NIR-responsive NaYF<inf>4</inf>:Yb,Tm/anatase TiO<inf>2</inf> composite aerogel Reviewed

    Fu Chih Li, Yoshitaka Kitamoto

    AIP Conference Proceedings   1929   020004   2018.1

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:American Institute of Physics Inc.  

    DOI: 10.1063/1.5021917

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  • Synthesis of multifunctional clustered nano-Fe<inf>3</inf>O<inf>4</inf> chitosan nanocomposite for biomedical applications Reviewed

    Maria Emma Villamin, Yoshitaka Kitamoto

    AIP Conference Proceedings   1929   020014   2018.1

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:American Institute of Physics Inc.  

    DOI: 10.1063/1.5021927

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  • Synthesis of drug carriers composed of gelatin and iron oxide nanoparticles with thermally responsive release capability Reviewed

    Seiko Oishi, Yoshitaka Kitamoto

    IEEJ Transactions on Fundamentals and Materials   137 ( 7 )   392 - 397   2017.7

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    Authorship:Last author, Corresponding author   Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Institute of Electrical Engineers of Japan  

    DOI: 10.1541/ieejfms.137.392

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  • Synthesis of magnetic thermo-responsive carriers consisting of Fe-Pt nanoparticles and hydroxypropyl cellulose Reviewed

    Yoshitaka Kitamoto, Wakako Murata

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   64 ( 7 )   359 - 363   2017.7

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Journal of the Japan Society of Powder and Powder Metallurgy  

    DOI: 10.2497/jjspm.64.359

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  • Relationship between ion concentration of ferrofluid and response signals of magnetic nanoparticles against ac magnetic fields Reviewed

    Shoya Oda, Yoshitaka Kitamoto

    AIP Advances   7 ( 5 )   056729   2017.5

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    Publishing type:Research paper (scientific journal)  

    DOI: 10.1063/1.4977973

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  • The role of Bgl2p in the transition to filamentous cells during biofilm formation by Candida albicans Reviewed

    Xinyue Chen, Ruoyu Zhang, Ayako Takada, Shun Iwatani, Chiemi Oka, Yoshitaka Kitamoto, Susumu Kajiwara

    Mycoses   60 ( 2 )   96 - 103   2017.2

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1111/myc.12554

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  • Fabrication of UCNPs/TiO<inf>2</inf> aerogel photocatalyst to improve photocatalytic performance Reviewed

    Fu Chih Li, Yoshitaka Kitamoto

    AIP Conference Proceedings   1807   020013   2017.1

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    Language:English   Publishing type:Research paper (international conference proceedings)  

    DOI: 10.1063/1.4974795

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  • Brownian particle-kinetics in a superparamagnetic ferrofluid subjected to static magnetic-field Reviewed

    Suko Bagus Trisnanto, Yoshitaka Kitamoto

    AIP Conference Proceedings   1807   020021   2017.1

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    Language:English   Publishing type:Research paper (international conference proceedings)  

    DOI: 10.1063/1.4974803

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  • Control and Manipulation of Nano- and Micro-structure in Magnetic Materials and Devices

    KITAMOTO Yoshitaka

    Journal of the Japan Society of Powder and Powder Metallurgy   64 ( 8 )   417 - 417   2017

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    Language:Japanese   Publisher:Japan Society of Powder and Powder Metallurgy  

    DOI: 10.2497/jjspm.64.417

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  • Fabrication of Bi-YIG/Au composite particles for magneto-optical devices Reviewed

    Yusuke Ishii, Yoshitaka Kitamoto

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   63 ( 10 )   882 - 886   2016.10

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    DOI: 10.2497/jjspm.63.882

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  • Structural Effects on Oxygen Reduction Activity of Carbon-Free Connected Platinum-Iron Nanoparticle Catalysts

    Hidenori Kuroki, Takanori Tamaki, Shiho Nakanishi, Masashi Matsumoto, Kei Kubobuchi, Masazumi Arao, Hideto Imai, Yoshitaka Kitamoto, Takeo Yamaguchi

    ECS Meeting Abstracts   MA2016-02 ( 38 )   2383 - 2383   2016.9

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    Publishing type:Research paper (scientific journal)   Publisher:The Electrochemical Society  

    We developed connected carbon-free platinum-iron (PtFe) nanoparticle catalysts with porous hollow capsule structure (Fig. 1) as oxygen-reduction-reaction (ORR) electrocatalysts for polymer electrolyte fuel cells (PEFCs).[1] This catalysts consist of a beaded network by connected PtFe nanoparticles with a crystallite size of 6~7 nm and a chemically-ordered (face centered tetragonal) superlattice structure. The beaded network is electrically conductive; thus, carbon-supports can be removed from catalyst layers in PEFCs. We have demonstrated that an MEA prepared using a carbon-free cathode of connected PtFe-nanoparticle catalysts was highly durable against start-up/shut-down operations because of the elimination of carbon-corrosion problems. Moreover, an ORR specific activity of a connected PtFe catalyst is about 9 times higher than that of a commercial Pt-nanoparticle catalyst supported on carbon black (Pt/C).

    In this study, the structural effects of a connected PtFe catalyst on an ORR activity were investigated in order to elucidate the factors of its high ORR activity. Note that the connected PtFe catalyst exhibited about twice higher ORR specific activity than the PtFe-nanoparticle catalyst (just nanoparticles without any connection between them) on carbon black. In addition, the ORR specific activity of the connected PtFe nanoparticles with hollow structure (with no supports) was 1.5 times higher than that of the connected PtFe nanoparticles on the electroconductive carbon support. These results indicate that the unique structures of connected nanoparticle catalysts, such as connected beaded network and hollow structure, enhance an ORR activity.

    We also have performed the refined structural analyses of a connected PtFe catalyst by using in-situ X-ray absorption spectroscopy (XAS) combined with Rietveld structure refinement with powder X-ray diffraction data, and spherical aberration corrected scanning transmission electron microscope (Cs-corrected STEM). The in-situ XAS analysis disclosed shorter Pt‒Pt bond distance and more Pt 5d vacancy of the connected PtFe catalyst compared with the commercial Pt/C. In addition, the Cs-corrected STEM observations revealed that the beaded network formed by connected PtFe nanoparticles possessed polycrystalline structure. In this presentation, the effects of the geometric and electronic structures of a connected PtFe catalyst on an ORR activity will be discussed in details. The knowledge obtained in this study provides guidelines for the design of ORR catalysts with enhanced ORR activities to achieve a high performance PEFC.

    [1] T. Tamaki, H. Kuroki, S. Ogura, T. Fuchigami, Y. Kitamoto, and T. Yamaguchi, “Connected nanoparticle catalysts possessing a porous, hollow capsule structure as carbon-free electrocatalysts for oxygen reduction in polymer electrolyte fuel cells”, Energy Environ. Sci., 2015, 8, 3545-3549.





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  • Heat generation of core-shell particles composed of biodegradable polymer and iron oxide Reviewed

    C Oka, K Ushimaru, N Horiishi, T Tsuge, Y Kitamoto

    Journal of the Magnetics Society of Japan   Vol. 40 ( No. 4 )   pp. 126 - 131   2016.4

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    A suspension of core-shell particles composed of a biodegradable polymer core and iron oxide nanoparticles (IONPs) exhibits higher heat generation under an alternating magnetic field compared with a suspension of IONPs at the same IONP concentration. The improvement of the heat generation will be attributed to the change of the strength of dipolar interactions between adjacent IONPs. The IONPs in the core-shell particles were relatively isolated, in contrast with that in IONP suspension before the formation of the core-shell particles. Therefore, in the core-shell particles, the dipolar interaction is reduced, and the heat-generating capability is increased. This explanation is brought through investigating the influence of the agglomerate size of IONPs on the heat-generating capability.

    DOI: 10.3379/msjmag.1605R009

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  • Nonlinearity of dynamic magnetization in a superparamagnetic clustered-particle suspension with regard to particle rotatability under oscillatory field Reviewed

    Suko Bagus Trisnanto, Yoshitaka Kitamoto

    Journal of Magnetism and Magnetic Materials   400   361 - 364   2016.2

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    DOI: 10.1016/j.jmmm.2015.07.016

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  • Composite of magnetic drug carriers with thermo-responsive polymer for controlled drug release Reviewed

    Jia Liu, Yoshitaka Kitamoto

    Japanese Journal of Applied Physics   55 ( 2 )   02BE02   2016.2

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    DOI: 10.7567/JJAP.55.02BE02

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  • Optimizing coil system for magnetic susceptometer with widely-adjustable field-strength and frequency Reviewed

    Suko Bagus Trisnanto, Yoshitaka Kitamoto

    Japanese Journal of Applied Physics   55 ( 2 )   02BD02   2016.2

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    DOI: 10.7567/JJAP.55.02BD02

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  • Biodegradable and magnetic core-shell composite particle prepared by emulsion solvent diffusion method Reviewed

    Chiemi Oka, Kazunori Ushimaru, Nanao Horiishi, Takeharu Tsuge, Yoshitaka Kitamoto

    Japanese Journal of Applied Physics   55 ( 2 )   02BE01   2016.2

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  • Fabrication of Langmuir-Blodgett Film of Surface-Modeified ZnO Nanoparticles Prepared by Solution Process Reviewed

    Yuhei Hasuike, Yoshitaka Kitamoto, Takeharu Tsuge, Masahiko Hara, Osamu Odawara, Hiroyuki Wada

    Trans. Mat. Res. Soc. Japan   Vol. 41 ( No. 1 )   p. 67 - 70   2016.2

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    ZnO nanoparticles were prepared by a solution method and a film of these nanoparticles was prepared by the Langmuir-Blodgett (LB) method. To prepare the LB film, the dispersibilities of ZnO nanoparticles in water and organic solvents were examined. The surface of the ZnO nanoparticles was modified by a surfactant, cetyltrimethylammonium bromide (CTAB), to improve their dispersibility. Using water as a solvent, dispersibility was improved by changing the CTAB concentration. However, aggregation of the nanoparticles occurred when they were transferred to chloroform to spread on water for fabrication of the LB film. With an organic solvent, aggregation of the ZnO nanoparticles in the LB film was improved when chloroform was used.

    DOI: 10.14723/tmrsj.41.67

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  • Influence of silica coating process on fine structure and magnetic properties of iron oxide nanoparticles Reviewed

    Liu Jia, Yoshitaka Kitamoto

    Electrochimica Acta   183   148 - 152   2015.11

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    DOI: 10.1016/j.electacta.2015.05.119

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  • Synthesis and characterization of sub-micrometer SiO<inf>2</inf>@NaYF<inf>4</inf>:Yb/Er beads and NaYF<inf>4</inf>:Yb/Er capsules for biomedical applications Reviewed

    Syed Mujtaba Ul Hassan, Yoshitaka Kitamoto

    Electrochimica Acta   183   160 - 164   2015.11

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    DOI: 10.1016/j.electacta.2015.04.051

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  • Facile fabrication of porous hollow upconversion capsules using hydrothermal treatment Reviewed

    Syed Mujtaba Ul Hassan, Yoshitaka Kitamoto

    Materials Chemistry and Physics   167   49 - 55   2015.11

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    DOI: 10.1016/j.matchemphys.2015.10.006

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  • Connected nanoparticle catalysts possessing a porous, hollow capsule structure as carbon-free electrocatalysts for oxygen reduction in polymer electrolyte fuel cells Reviewed

    Takanori Tamaki, Hidenori Kuroki, Shun Ogura, Teruaki Fuchigami, Yoshitaka Kitamoto, Takeo Yamaguchi

    Energy and Environmental Science   8 ( 12 )   3545 - 3549   2015.10

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    DOI: 10.1039/c5ee02450a

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  • Optical properties of Y2Si2O7:Ce,Tb nanoparticles prepared by reverse micelle method Reviewed

    Takashi Akino, Anna Gubarevich, YOSHITAKA KITAMOTO, OSAMU ODAWARA, Hiroyuki Wada

    Transactions of the Material Research Society of Japan   Vol. 40 ( No. 3 )   pp. 287 - 290   2015.9

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  • Ptfe Porous Hollow Nanocapsule Electrocatalysts with Remarkably Enhanced Oxygen Reduction Activity

    Hidenori Kuroki, Takanori Tamaki, Shiho Nakanishi, Masashi Matsumoto, Kazuhiro Kamiguchi, Kei Kubobuchi, Masazumi Arao, Hideto Imai, Yoshitaka Kitamoto, Takeo Yamaguchi

    ECS Meeting Abstracts   MA2015-02 ( 37 )   1332 - 1332   2015.7

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    Expansion of the commercial applications of polymer electrolyte fuel cells (PEFCs) strongly requires great improvements in cost, performance, and durability. At a cathode where oxygen reduction reaction (ORR) occurs, platinum (Pt) catalysts show sluggish ORR leading to high cost and poor performance of PEFCs. In addition, carbon-supports for Pt catalyst degrade due to carbon-corrosion during start-up/shut-down operations; it results in a severe deterioration of PEFC performance.

    Here we develop platinum-iron (PtFe) porous hollow nanocapsules (Fig. 1) as carbon-free electrocatalysts for ORR. The nanocapsules are composed of fused PtFe nanoparticles with a crystallite size of 6-7 nm and a chemically-ordered (face-centered tetragonal; fct) structure. The fused PtFe network possesses an electron conductivity, thus any carbon-support is not required at the cathode made of PtFe nanocapsules. We demonstrated the MEA using the carbon-free cathode catalyst-layer of PtFe nanocapsules exhibited sufficiently high IV performance, and excellent durability against start-up/shut-down operations at 80°C, by intrinsically eliminating the problem of carbon-corrosion.[1] The exclusion of carbon-supports from the cathode catalyst layer also enabled the formation of the ultrathin catalyst-layer that would provide great advantages to mass transport of oxygen. Moreover, it is noteworthy that the specific ORR activity of the PtFe nanocapsule is approximately 8.5 times higher than that of the commercial Pt catalyst supported on carbon black (Pt/C). Interestingly, the specific activity of the nanocapsule is also 2~3 times enhanced, compared with that of fct-PtFe nanoparticles (without any fused networks) supported on carbon black. Thus, it implies that the unique structures of the nanocapsule, such as the connected network structure of fused PtFe metal nanoparticles, and the support-free structure, would allow to exhibit higher ORR activities. We have also investigated the structure and electronic structure via in-situx-ray absorption spectroscopy combined with electron diffraction and Rietveld structure refinement with powder x-ray diffraction data.

    In this presentation, the relationship of the surface structures on the PtFe nanocapsules to their ORR activities will be discussed in details. The above results indicate that the newly-developed nanocapsule is a quite promising catalyst-layer material because it potentially can solve all the current problems, regarding ORR activity, durability, and mass-transport of oxygen, in the conventional cathode catalyst layers using Pt-based catalysts on carbon supports.

    [1] T. Tamaki, H. Kuroki, S. Ogura, T. Fuchigami, Y. Kitamoto, and T. Yamaguchi, “Pt-Fe Porous Hollow Nanocapsule as Carbon-free Electrocatalyst for Oxygen Reduction”, Submitted.

    Fig. 1. Schematic illustration of PtFe porous hollow nanocapsules as carbon-free electrocatalysts.

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  • Initial growth process of Co (Pd) layers on a Pd (Co) surface Reviewed

    N. Nishizawa, J. G. Porquez, Y. Kitamoto, H. Munekata

    Journal of Applied Physics   117 ( 17 )   p. 17A720   2015.5

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  • Core-shell composite particles composed of biodegradable polymer particles and magnetic iron oxide nanoparticles for targeted drug delivery Reviewed

    Chiemi Oka, Kazunori Ushimaru, Nanao Horiishi, Takeharu Tsuge, Yoshitaka Kitamoto

    Journal of Magnetism and Magnetic Materials   381   278 - 284   2015.5

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  • Optical properties of silica-coated Y<inf>2</inf>O<inf>3</inf>:Er,Yb nanoparticles in the presence of polyvinylpyrrolidone Reviewed

    Kunio Fujii, Yoshitaka Kitamoto, Masahiko Hara, Osamu Odawara, Hiroyuki Wada

    Journal of Luminescence   156   8 - 15   2014.12

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    DOI: 10.1016/j.jlumin.2014.06.055

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  • Field-dependent Brownian relaxation dynamics of a superparamagnetic clustered-particle suspension Reviewed

    S. B. Trisnanto, Y. Kitamoto

    Physical Review E - Statistical, Nonlinear, and Soft Matter Physics   90 ( 3 )   p. 032306   2014.9

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    DOI: 10.1103/PhysRevE.90.032306

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  • Incidence Angle and Polarization Dependence of Photo-Induced FMR in Co/Pd Multilayers Reviewed

    J. Saeki, K. Nishibayashi, T. Matsuda, Y. Kitamoto, H. Munekata

    Journal of the Magnetics Society of Japan   Vol. 38 ( No. 3-2 )   p. 151 - 155   2014.5

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  • Modeling of semi-shell nanostructures formed by metal deposition on dielectric nanospheres and numerical evaluation of plasmonic properties Reviewed

    Ryushi Fujimura, Ruzhi Zhang, Yoshitaka Kitamoto, Masayuki Shimojo, Kotaro Kajikawa

    Japanese Journal of Applied Physics   53 ( 3 )   2014.3

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    DOI: 10.7567/JJAP.53.035201

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  • Device for controlled distribution of FePt nanoparticles formations in a stream of liquid medium under influence of magnetic field

    Karolis Šileika, Yoshitaka Kitamoto, Bronius Bakšys, Inga Skiedraite

    Medziagotyra   20 ( 1 )   30 - 35   2014

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    DOI: 10.5755/j01.ms.20.1.3371

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  • Biodegradable polymer-based composite particles for targeted drug delivery carriers with magnetic response Reviewed

    Y. Kitamoto, C. Oka, K. Ushimaru, T. Tsuge, N. Horiishi

    Technical Proceedings of the 2014 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2014   2   319 - 322   2014

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  • Growth of Fe-Pt magnetic nanoparticles on silica particles modified with organic molecules Reviewed

    Yoshitaka Kitamoto, Teruaki Fuchigami, Yoshihisa Namiki

    Japanese Journal of Applied Physics   52 ( 11 PART 1 )   p. 110114   2013.11

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  • Magnetic sensor for sentinel lymph node biopsy

    Yoshitaka Kitamoto, Takaaki Masaki, Masanori Abe, Tomoaki Ueda

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   60 ( 3 )   128 - 131   2013.3

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  • Magnetic Beads Composed of FePt/Au Hybrid Nanoshell and Silica Core Reviewed

    R. Zhang, T. Hamada, S. Inagi, Y. Kitamoto

    Journal of the Magnetics Society of Japan   Vol. 37 ( No. 3-2 )   pp. 303 - 306   2013.2

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  • Artificial material manipulation of magnetic anisotropy in FePt magnetic nanoparticles through application of hydrostatic pressure

    M. Mito, Y. Komorida, H. Deguchi, T. Tajiri, T. Iwamoto, Y. Kitamoto

    Journal of Applied Physics   113 ( 4 )   2013.1

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    DOI: 10.1063/1.4776767

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  • Low-power photo-induced precession of magnetization in ultra-thin Co/Pd multilayer films Reviewed

    K. Yamamoto, T. Matsuda, K. Nishibayashi, Y. Kitamoto, H. Munekata

    IEEE Transactions on Magnetics   49 ( 7 )   3155 - 3158   2013

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    DOI: 10.1109/TMAG.2013.2240379

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  • Magnetically guided drug delivery system using magnetic capsules

    Yoshitaka Kitamoto

    Journal of the Institute of Electrical Engineers of Japan   133 ( 2 )   80 - 82   2013

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    DOI: 10.1541/ieejjournal.133.80

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  • Afterglow Properties of Silica-Capped Sr2MgSi2O7:Eu,Dy Nanoparticles Prepared by Laser Ablation in Ethanol Reviewed

    Mika Ishizaki, Teruaki Fuchigami, Takao Katagiri, Takao Sasagawa, Yoshitaka Kitamoto, Osamu Odawara, Hiroyuki Wada

    CheM   vol. 2   p. 47 - 51   2012.11

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  • Inorganic-organicmagneticnanocomposites for use in preventive medicine: A rapid and reliable elimination system for cesium Reviewed

    Yoshihisa Namiki, Tamami Namiki, Yukiko Ishii, Shigeo Koido, Yuki Nagase, Akihito Tsubota, Norio Tada, Yoshitaka Kitamoto

    Pharmaceutical Research   29 ( 5 )   1404 - 1418   2012.5

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    DOI: 10.1007/s11095-011-0628-x

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  • Optical Properties of Y2O3:Er,Yb Nanoparticle Prepared by Laser Ablation in Liquid Reviewed

    Yuji Onodera, Takashi Nunokawa, Kazutaka Nakamura, Yoshitaka Kitamoto, Osamu Odawara, Hiroyuki Wada

    2012.5

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  • A magnetically guided anti-cancer drug delivery system using porous FePt capsules Reviewed

    Teruaki Fuchigami, Ryo Kawamura, Yoshitaka Kitamoto, Masaru Nakagawa, Yoshihisa Namiki

    Biomaterials   33 ( 5 )   1682 - 1687   2012.2

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    DOI: 10.1016/j.biomaterials.2011.11.016

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  • Preparation of InP Nanoparticles by Laser Ablation in Liquid Reviewed

    Shunsuke Kagaya, Yoshitaka Ehara, Yoshitaka Kitamoto, Hiroshi Funakubo, Masahiko Hara, Yohtaro Yamazaki, Osamu Odawara, Hiroyuki Wada

    The Review of Laser Engineering   vol. 40 ( no. 2 )   p. 117 - 121   2012.2

  • Magnetic sensor for sentinel lymph node biopsy using superparamagnetic beads Reviewed

    Yoshitaka Kitamoto, Takaaki Masaki, Suko Bagus Trisnanto, Tomoaki Ueda, Masanori Abe

    Proceedings of IEEE Sensors   103 - 106   2012

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    DOI: 10.1109/ICSENS.2012.6411180

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  • Preparation of SiO <inf>2</inf> -Capped Sr <inf>2</inf> MgSi <inf>2</inf>O <inf>7</inf>:Eu,Dy nanoparticles with laser ablation in liquid Reviewed

    Mika Ishizaki, Takao Katagiri, Takao Sasagawa, Yoshitaka Kitamoto, Osamu Odawara, Hiroyuki Wada

    Journal of Nanotechnology   Vol. 2012   435205   2012

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    DOI: 10.1155/2012/435205

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  • Size-tunable drug-delivery capsules composed of a magnetic nanoshell Reviewed

    Teruaki Fuchigami, Yoshitaka Kitamoto, Yoshihisa Namiki

    Biomatter   2 ( 4 )   313 - 320   2012

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    DOI: 10.4161/biom.22617

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  • Detecting ferrite nanobeads for sentinel lymph node mapping with a highly sensitive hall differential magnetic field sensor Reviewed

    M. Abe, T. Ueda, T. Masaki, Y. Kitamoto, N. Matsushita, H. Handa

    Journal of Physics: Conference Series   352 ( 1 )   012015   2012

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    DOI: 10.1088/1742-6596/352/1/012015

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  • Nanomedicine for cancer: Lipid-based nanostructures for drug delivery and monitoring Reviewed

    Yoshihisa Namiki, Teruaki Fuchigami, Norio Tada, Ryo Kawamura, Satoshi Matsunuma, Yoshitaka Kitamoto, Masaru Nakagawa

    Accounts of Chemical Research   44 ( 10 )   1080 - 1093   2011.10

  • Magnetic anisotropy and magnetization reversal of (Ga,Mn)As dot-array Reviewed

    H. Kimura, S. Kobayashi, T. Yamaguchi, Y. Kitamoto, H. Munekata

    Journal of Applied Physics   109 ( 7 )   p. 07C319   2011.4

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  • Ferromagnetic FePt-nanoparticles/polycation hybrid capsules designed for a magnetically guided drug delivery system Reviewed

    Teruaki Fuchigami, Ryo Kawamura, Yoshitaka Kitamoto, Masaru Nakagawa, Yoshihisa Namiki

    Langmuir   27 ( 6 )   2923 - 2928   2011.3

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    DOI: 10.1021/la1041019

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  • Langmuir-Blodgett法を用いた酸化亜鉛ナノ粒子薄膜の作製と評価 Reviewed

    蓮池悠平, 北本仁孝, 原正彦, 小田原修, 和田裕之

    2011.3

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  • Preparation and optical properties of rare earth doped Y<inf>2</inf>O <inf>3</inf> nanoparticles synthesized by thermal decomposition with oleic acid Reviewed

    N. Takahashi, A. Gubarevich, J. Sakurai, S. Hata, T. Tsuge, Y. Kitamoto, Y. Yamazaki, O. Odawara, H. Wada

    Advanced Materials Research   332-334   1974 - 1978   2011

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    DOI: 10.4028/www.scientific.net/AMR.332-334.1974

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  • Particle-diameter dependence of the coercive field in FePt nanoparticles with a face-centered tetragonal structure

    M. Mito, Y. Komorida, N. J.O. Silva, H. Tsuruda, H. Deguchi, S. Takagi, T. Tajiri, T. Iwamoto, Y. Kitamoto

    Journal of Applied Physics   108 ( 12 )   2010.12

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    DOI: 10.1063/1.3524190

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  • Magnetic anisotropy and magnetization reversal of (Ga,Mn)As dot-array Reviewed

    H. Kimura, Y. Kitamoto, H. Munekata, S. Kobayashi

    Abstract Booklet PASPS-15   p. 53   2010.12

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  • Magnetic anisotropy and magnetization reversal of (Ga,Mn)As dots Reviewed

    H. Kimura, Y. Kitamoto, H. Munekata

    Abstract booklet of 55th-MMM   p. 518   2010.11

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  • (Ga,Mn)Asドットの磁気異方性と磁化反転 Reviewed

    木村浩樹, 北本仁孝, 宗片比呂夫

    講演予稿集   p. 10 - 074   2010.9

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  • FePt/SiO2複合型磁性ナノ粒子の作製 Reviewed

    渕上輝顕, 河村亮, 山崎陽太郎, 北本仁孝, 中川勝, 並木禎尚

    粉体および粉末冶金   Vol. 57 ( No. 9 )   pp. 636 - 641   2010.9

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  • Fabrication of FePt/SiO<inf>2</inf> composite magnetic beads Reviewed

    Teruaki Fuchigami, Ryo Kawamura, Yohtaro Yamazaki, Yoshitaka Kitamoto, Masaru Nakagawa, Yoshihisa Namiki

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   57 ( 9 )   636 - 641   2010.9

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  • Magneto-transport properties of a single (Ga,Mn)As dot Reviewed

    H. Kimura, Y. Kitamoto, H. Munekata

    Abstract PASPS-VI   p. 43 - 44.   2010.8

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  • Langmuir-Blodgett法を用いた酸化亜鉛ナノ粒子薄膜の作製と評価 Reviewed

    蓮池悠平, 北本仁孝, 原正彦, 小田原修, 和田裕之

    電気化学会第77回大会   2010.4

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  • Optical properties of dispersed ZnO nanoparticles synthesized by precipitation method Reviewed

    Shotaro Takahashi, Atsushi Noguchi, Takeharu Tsuge, Yoshitaka Kitamoto, Yohtaro Yamazaki, Osamu Odawara, Hiroyuki Wada

    Far East Journal of Mechanical Engineering and Physics   Vol. 1 ( No. 1 )   p. 7   2010.3

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  • Observation of two kinds of ESR spectra in FePt nanoparticles

    H. Tsuruda, Y. Komorida, M. Mito, H. Deguchi, S. Takagi, T. Iwamoto, Y. Kitamoto

    Journal of Physics: Conference Series   200 ( SECTION 7 )   2010

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    DOI: 10.1088/1742-6596/200/7/072102

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  • Chemical synthesis of FePt nanoparticles with high alternate current magnetic susceptibility for biomedical applications Reviewed

    Yoshitaka Kitamoto, Jing Sha He

    Electrochimica Acta   54 ( 25 )   5969 - 5972   2009.10

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    DOI: 10.1016/j.electacta.2009.02.092

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  • Chemical synthesis of Fe-Pt nanoparticles protected with water-soluble polymer for biomedical applications Reviewed

    Yoshitaka Kitamoto, Jing Sha He, Yohtaro Yamazaki

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   56 ( 9 )   568 - 573   2009.9

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    DOI: 10.2497/jjspm.56.568

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  • Anomalous magnetic behavior in FePt nanoparticles chemically synthesized with polymer protective agent

    Takashi Iwamoto, Yoshitaka Kitamoto, Naoki Toshima

    Physica B: Condensed Matter   404 ( 14-15 )   2080 - 2085   2009.7

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    DOI: 10.1016/j.physb.2009.03.048

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  • Chemical synthesis of FePt/Fe-oxide core/shell nanoparticles Reviewed

    Yoshitaka Kitamoto, Kenichiro Kimura, Yohtaro Yamazaki

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   56 ( 3 )   121 - 126   2009.3

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    DOI: 10.2497/jjspm.56.121

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  • Improvement in resonant frequency of magnetic domain wall displacement in soft magnetic thin films by slit patterning Reviewed

    Taku Masai, Yoshitaka Kitamoto

    Japanese Journal of Applied Physics   48 ( 8 Part 1 )   0830011 - 0830015   2009

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    DOI: 10.1143/JJAP.48.083001

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  • Annealing-induced solid-phase epitaxy at interfaces between CoFeB layers and MgO barrier-layer in CoFeB/MgO/CoFeB magnetic tunnel junctions and their magnetic properties

    Y. Kitamoto, T. Takeuchi, K. Tsunekawa, Y. S. Choi, Y. Nagamine, D. D. Djayaprawira

    ECS Transactions   16 ( 45 )   37 - 44   2009

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    DOI: 10.1149/1.3140008

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  • Effect of slit patterning perpendicular to magnetic easy axis in thin film inductors Reviewed

    Taku Masai, Yoshitaka Kitamoto

    IEEE Transactions on Magnetics   44 ( 11 PART 2 )   3871 - 3874   2008.11

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    DOI: 10.1109/TMAG.2008.2002476

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  • Fabrication of ferromagnetic Ni epitaxial thin film by way of hydrogen reduction of NiO

    Akifumi Matsuda, Shusaku Akiba, Masayasu Kasahara, Takahiro Watanabe, Yasuyuki Akita, Yoshitaka Kitamoto, Takeo Tojo, Hitoshi Kawaji, Tooru Atake, Kouji Koyama, Mamoru Yoshimoto

    Thin Solid Films   516 ( 12 )   3873 - 3876   2008.4

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    DOI: 10.1016/j.tsf.2007.07.133

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  • 磁気光学顕微鏡による(Ga,Mn)Asの磁化反転過程の局所観察 Reviewed

    青山淳, 野村健太, 橋本佑介, 小林暁, 深谷新平, 北本仁孝, 宗片比呂夫

    第2分冊   p. 782   2008.3

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  • Crystallization of amorphous CoFeB ferromagnetic layers in CoFeB/MgO/CoFeB magnetic tunnel junctions Reviewed

    Takashi Takeuchi, Koji Tsunekawa, Young Suk Choi, Yoshinori Nagamine, David D. Djayaprawira, Akira Genseki, Yoichi Hoshi, Yoshitaka Kitamoto

    Japanese Journal of Applied Physics, Part 2: Letters   46 ( 25-28 )   L623 - L626   2007.7

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    DOI: 10.1143/JJAP.46.L623

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  • Direct synthesis of fct-structured FePt nanoparticles at low temperature with assistance of poly(N-vinyl-2-pyrrolidone)

    Takashi Iwamoto, Kinya Matsumoto, Yoshitaka Kitamoto, Naoki Toshima

    Journal of Colloid and Interface Science   308 ( 2 )   564 - 567   2007.4

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    DOI: 10.1016/j.jcis.2007.01.049

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  • Direct synthesis of ferromagnetic FePt nanoparticles by using a high-pressure chemical solution route with microwave irradiation Reviewed

    Yoshitaka Kitamoto, Rumiko Minami, Tsukasa Chikata, Shunsaku Kato

    ECS Transactions   3 ( 25 )   259 - 266   2007

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    DOI: 10.1149/1.2753258

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  • Structural study of CoFeB/MgO/CoFeB magnetic tunnel junctions

    K. Tsunekawa, Y. S. Choi, Y. Nagamine, D. D. Djayaprawira, N. Watanabe, T. Takeuchi, Y. Kitamoto

    ECS Transactions   3 ( 25 )   413 - 421   2007

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    DOI: 10.1149/1.2753273

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  • Influence of chemical composition of CoFeB on tunneling magnetoresistance and microstructure in polycrystalline CoFeB/MgO/CoFeB magnetic tunnel junctions

    Koji Tsunekawa, Young Suk Choi, Yoshinori Nagamine, David D. Djayaprawira, Takashi Takeuchi, Yoshitaka Kitamoto

    Japanese Journal of Applied Physics, Part 2: Letters   45 ( 42-45 )   L1152 - L1155   2006.11

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    DOI: 10.1143/JJAP.45.L1152

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  • Magnetic anisotropy switching in (Ga,Mn)As with increasing hole concentration

    K. Hamaya, T. Watanabe, T. Taniyama, A. Oiwa, Y. Kitamoto, Y. Yamazaki

    PHYSICAL REVIEW B   74 ( 4 )   045201_1-5   2006.7

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    DOI: 10.1103/PhysRevB.74.045201

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  • Analysis of atomic arrangement in magnetic Fe-Pt nanoparticles

    H. Sakuma, T. Taniyama, K. Ishii, Y. Kitamoto, Y. Yamazaki

    Journal of Magnetism and Magnetic Materials   300 ( 2 )   284 - 292   2006.5

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    DOI: 10.1016/j.jmmm.2005.05.016

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  • Dynamic relaxation of magnetic clusters in a ferromagnetic (Ga,Mn)As epilayer

    K Hamaya, T Koike, T Taniyama, T Fujii, Y Kitamoto, Y Yamazaki

    PHYSICAL REVIEW B   73 ( 15 )   155204_1-7   2006.4

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    DOI: 10.1103/PhysRevB.73.155204

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  • Dynamic relaxation of magnetic clusters in a ferromagnetic (Ga,Mn)As epilayer Reviewed

    K. Hamaya, T. Koike, T. Taniyama, T. Fujii, Y. Kitamoto, Y. Yamazaki

    Physical Review B - Condensed Matter and Materials Physics   73 ( 15 )   pp. 155204 - 1   2006

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    DOI: 10.1103/PhysRevB.73.155204

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  • Magnetic anisotropy switching in (Ga,Mn)As with increasing hole concentration Reviewed

    K. Hamaya, T. Watanabe, T. Taniyama, A. Oiwa, Y. Kitamoto, Y. Yamazaki

    Physical Review B - Condensed Matter and Materials Physics   74 ( 4 )   2006

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    DOI: 10.1103/PhysRevB.74.045201

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  • Magnetic Properties of L10 Fe-Ni-Pt Films for Heat Assisted Magnetic Recording

    Kaneko Masahiko, Sueki Kengo, Kitamoto Yoshitaka

    Journal of the Magnetics Society of Japan   30 ( 6 )   588 - 591   2006

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    Very high uniaxial anisotropy Ku as well as a moderate Curie temperature is required for magnetic materials by heat assisted magnetic recording (HAMR). Crystalline structure and magnetic properties of Fe-Ni-Pt thin films deposited on quarts glass substrates have been investigated in order to obtain optimum composition for the HAMR. L10 phase is found in Fe60-xNixPt40 (x = 0 to 24) with c-axis aligned in the perpendicular direction to the film plane. As Ni content x increases, the quality of (001) orientation is improved, while the order parameter S is gradually degraded. As a result, Ku in the perpendicular direction to the film plane is decreased from 3 x 107 erg/cm3 for Fe60Pt40 to 1 x 107 erg/cm3 for Fe45Ni15Pt40 film. The Curie temperature measured is decreased with Ni content to 320°C for Fe45Ni15Pt40. Thermal simulation on the Fe-Ni-Pt disk assuming the similar film structure as current perpendicular recording media has revealed that the temperature rise above 350°C is available by the laser irradiation with a power of 2 mW and pulse width of 2 ns. Therefore, Fe-Ni-Pt can be a candidate material with high anisotropy and optimum Curie temperature suitable for the HAMR.

    DOI: 10.3379/jmsjmag.30.588

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  • Fabrication of L10 Ordered Fe-Ni-Pt Films and Their Magnetic Properties

    Sueki K., Kitamoto Y., Kaneko M.

    Journal of the Magnetics Society of Japan   30 ( 2 )   131 - 134   2006

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    Since L10 ordered Fe-Pt has very high uniaxial magnetic anisotropy, it is an attractive candidate for ultra-high-density storage using heat-assisted magnetic recording. But its Curie temperature of 500 °C needs to be lowered if a temperature rise above the Curie temperature is to be achieved by the use of moderate laser power. Control of the Curie temperature was investigated in Fe60-xNixPt40 thin films sputtered on quartz glass substrates. L10 phase (001) texture was found in all the films with x = 0 to 24, indicating that the crystalline structure is L10 phase. XRD rocking curves revealed that the (001) orientation is much improved as x increases, while the order parameter S is gradually degraded, and magnetic anisotropy energy is decreased. A Curie temperature of around 300 °C, which may be suitable for heat-assisted magnetic recording, is obtained for x = 20 to 24.

    DOI: 10.3379/jmsjmag.30.131

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  • Magnetocrystalline anisotropy of partially ordered Fe-Pt nanoparticles directly synthesized with microwave-polyol method

    Yoshitaka Kitamoto, Rumiko Minami, Yuuki Shibata, Tsukasa Chikata, Shunsaku Kato

    IEEE Transactions on Magnetics   41 ( 10 )   3880 - 3882   2005.10

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    DOI: 10.1109/TMAG.2005.854953

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  • Magnetic properties and microstructure of isolated Fe-Pt nanoparticle-monolayer assembly by protective coating

    Mu Pei Chen, Kazuya Kuroishi, Yoshitaka Kitamoto

    IEEE Transactions on Magnetics   41 ( 10 )   3376 - 3378   2005.10

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    DOI: 10.1109/TMAG.2005.855350

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  • Magnetization reversal with domain-wall pinning in (Ga, Mn)As wire

    T. Koike, K. Hamaya, N. Funakoshi, Y. Takemura, Y. Kitamoto, H. Munekata

    IEEE Transactions on Magnetics   41 ( 10 )   2742 - 2744   2005.10

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    DOI: 10.1109/TMAG.2005.854730

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  • Microstructural and magnetic study of nanocrystalline soft magnetic thin films of Fe-C and Fe-Co-C deposited with sputtering

    Yoshitaka Kitamoto, Hiroyuki Tagami, Goro Kiyota

    IEEE Transactions on Magnetics   41 ( 10 )   3295 - 3297   2005.10

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    DOI: 10.1109/TMAG.2005.854719

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  • L10相Fe-Ni-Ptの製膜と磁気特性 Reviewed

    末木謙吾, 北本仁孝, 金子正彦

    第29回日本応用磁気学会学術講演会概要   21pA - 13   2005.9

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  • Ion irradiation control of ferromagnetism in (Ga,Mn)as

    Hiroaki Kato, Kohei Hamaya, Tomoyasu Taniyama, Yoshitaka Kitamoto, Hiro Munekata

    Japanese Journal of Applied Physics, Part 2: Letters   44 ( 24-27 )   L816 - L818   2005.6

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    DOI: 10.1143/JJAP.44.L816

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  • Correlation between ferromagnetism and hole localization in very thin (Ga,Mn)As epilayers

    K. Hamaya, Y. Kitamoto, Y. Yamazaki, T. Taniyama, R. Moriya, H. Munekata

    Journal of Applied Physics   97 ( 10 )   10D301   2005.5

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    DOI: 10.1063/1.1844731

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  • Effect of Ga + irradiation on magnetic and magnetotransport properties in (Ga,Mn)As epilayers

    H. Kato, K. Hamaya, Y. Kitamoto, T. Taniyama, H. Munekata

    Journal of Applied Physics   97 ( 10 )   10D302   2005.5

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    DOI: 10.1063/1.1844751

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  • Activation volume and magnetization reversal of nanoparticle films composed of magnetically isolated Fe-Pt nanoparticles

    Mu Pei Chen, Hiroaki Nishio, Yoshitaka Kitamoto, Hiroshi Yamamoto

    Journal of Applied Physics   97 ( 10 )   10J321   2005.5

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    DOI: 10.1063/1.1861274

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  • Mixed magnetic phases in (Ga, Mn)As epilayers

    K. Hamaya, T. Taniyama, Y. Kitamoto, T. Fujii, Y. Yamazaki

    Physical Review Letters   94 ( 14 )   147203   2005.4

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    DOI: 10.1103/PhysRevLett.94.147203

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  • CoZrNb/Fe-C discontinuous multilayer films for GHz applications Reviewed

    KK Choi, T Murase, Y Fujikawa, Y Kitamoto, Y Yamazaki

    NINTH INTERNATIONAL CONFERENCE ON FERRITES (ICF-9)   171 - 176   2005

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  • Influence of chemical conditions in fabrication of Bi-YIG precursor on morphological and magneto-optical response of its particulate film Reviewed

    CS Kuroda, K Uchida, F Ikazaki, T Taniyama, Y Kitamoto, Y Yamazaki

    NINTH INTERNATIONAL CONFERENCE ON FERRITES (ICF-9)   425 - 430   2005

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  • 第5版実験化学講座28-ナノテクノロジーの化学-(分担) Reviewed

    北本仁孝

    2005

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  • Magnetocrystalline anisotropy of partially ordered Fe-Pt nanoparticles directly synthesized by microwave-polyol method

    Y. Kitamoto, R. Minami, T. Chikata, S. Kato

    INTERMAG ASIA 2005: Digests of the IEEE International Magnetics Conference   828   2005

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    DOI: 10.1109/intmag.2005.1464261

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  • Significant change in in-plane magnetic anisotropy of (Ga,Mn)As epilayer induced by low-temperature annealing

    H Kato, K Hamaya, T Taniyama, Y Kitamoto, H Munekata

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   43 ( 7A )   L904 - L906   2004.7

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    DOI: 10.1143/JJAP.43.L904

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  • Influence of the particle size distribution on magneto-optical properties of Bi-YIG particulate film Reviewed

    C.S. Kuroda, T. Taniyama, Y. Kitamoto, Y. Yamazaki, K. Uchida, F. Ikazaki

    Trans. MRS-J Jpn   29 ( 4 )   1627 - 1630   2004.6

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  • Anisotropy field distribution of partially ordered FePt nanoparticles

    H Sakuma, T Taniyama, Y Kitamoto, Y Yamazaki, H Nishio, H Yamamoto

    JOURNAL OF APPLIED PHYSICS   95 ( 11 )   7261 - 7263   2004.6

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    DOI: 10.1063/1.1669352

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  • Contribution of shape anisotropy to the magnetic configuration of (Ga, Mn)As

    K Hamaya, R Moriya, A Oiwa, T Taniyama, Y Kitamoto, Y Yamazaki, H Munekata

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   43 ( 2B )   L306 - L308   2004.2

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    DOI: 10.1143/JJAP.43.L306

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  • Temperature-Dependent Magnetic Properties of Fe-Pt Nanoparticles

    H. Sakuma, T. Taniyama, H. Nishio, Y. Kitamoto, Y, Yamazaki H Yamamoto

    Trans. Magn. Soc. Japan   4 ( 4-2 )   204 - 207   2004

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    This project investigated the temperature dependence of the magnetization and anisotropy field of Fe-Pt nanoparticle samples with different order parameters and compositions. A decrease in the order parameter and/or deviation from equiatomic composition brings about a rapid reduction in the magnetization and anisotropy field with increasing temperature. The temperature dependence of the magnetic properties was found to be associated with the probability of Fe atoms being in Ll0type atomic arrangement, which was obtained using Mossbauer spectroscopy, rather than with the order parameter. The changes in magnetization and anisotropy field correlated with each other and demonstrated a qualitative relationship in agreement with a theory based on magnetic thermal fluctuation.

    DOI: 10.3379/tmjpn2001.4.204

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  • Anisotropic Magnetotransport due to uniaxial magnetic anisotropy in (Ga,Mn)As wires

    K. Hamaya, T. Taniyama, Y. Kitamoto, R. Moriya, H. Munekata

    IEEE Trans. on Magn.   40 ( 4 )   2682 - 2884   2004

  • Novel nanoparticle milling process for Bi-YIG dispersed transparent films Reviewed

    TY Kim, T Hirano, Y Kitamoto, Y Yamazaki

    IEEE TRANSACTIONS ON MAGNETICS   39 ( 4 )   2078 - 2080   2003.7

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    DOI: 10.1109/TMAG.2003.814289

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  • Control of magnetic features in epitaxial micro-patterned (Ga,Mn)As wire structures Reviewed

    K. Hamaya, R. Moriya, A. Oiwa, T. Taniyama, Y. Kitamoto, H. Munekata

    Intermag 2003 - Program of the 2003 IEEE International Magnetics Conference   2003

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    DOI: 10.1109/INTMAG.2003.1230405

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  • Selective dry etching of manganite thin films for high sensitive magnetoresistive sensors Reviewed

    M. Naoe, K. Hamaya, N. Fujiwara, T. Taniyama, Y. Kitamoto, Y. Yamazaki

    J. Magn. Magn. Mater.   235 ( 1-3 )   223 - 226   2001.10

  • Enhanced magnetoresistance of La1-xSrxMnO3 thin films by reaction with substrates Reviewed

    K. Hamaya, T. Taniyama, Y. Kitamoto, Y. Yamazaki

    J. Magn. Soc. Jpn.   25 ( 4-2 )   727 - 730   2001.4

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    Magnetic and magnetotransport properties of polycrystalline La1-xSrxMnO3 (LSMO) thin films annealed at high temperatures were investigated. The reaction of the LSMO thin films with YSZ substrates effectively induces enhancement of low-field MR up to 13.8 % at 78 K for the film annealed at 1350°C. The results are consistently explained by the formation of potential barriers at grain boundaries by the annealing.

    DOI: 10.3379/jmsjmag.25.727

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  • Faraday effect enhancement in Co-ferrite layer incorporated into one-dimensional photonic crystal working as a Fabry-Perot resonator Reviewed

    E. Takeda, N. Todoroki, Y. Kitamoto, M. Abe, M. Inoue, T. Fujii, K. I. Arai

    J. Appl. Phys.   87 ( 9 )   6782 - 6784   2000.5

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  • Influence of Zn ferrite underlayers on noise characteristics of Co-Ni ferrite-plated perpendicular recording disks

    Yoshitaka Kitamoto, Fuchun Zhang, Masanori Abe, Masahiko Naoe

    Digests of the Intermag Conference   2000

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  • Developing Perpendicular Magnetic Recording Media by Ferrite Plating from Aqueous Solution

    ABE M., KITAMOTO Y.

    ITE Technical Report   23 ( 68 )   57 - 63   1999.11

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    For applying to perpendicular magnetic recording, ferrite films are prepared by ferrite plating from an aqueous solution at 85-90℃;Co-ferrite films for recording media and NiZn ferrite films for high permeability underlayers. The Co-ferrite films have a prominent perpendicular magnetic anisotropy, exhibiting excellent magnetic hysteresis loops with Hc=〜3200Oe. This paper describes improvement of magnetic properties of the ferrite films by optimizing plating conditions, and reports preliminary results of signal retrival performed on the Co-ferrite films.

    DOI: 10.11485/itetr.23.68.0_57

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  • The permeability of plated ferrite films Reviewed

    PJ van der Zaag, P Lubitz, Y Kitamoto, M Abe

    IEEE TRANSACTIONS ON MAGNETICS   35 ( 5 )   3436 - 3438   1999.9

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  • Ultrasound enhanced ferrite plating of polymer microspheres for magnetic cellular segregation Reviewed

    M Ojima, F Shirasaki, Y Kitamoto, M Abe, S Nagahata

    IEEE TRANSACTIONS ON MAGNETICS   35 ( 5 )   4118 - 4120   1999.9

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  • Electro-ferrite plating of magnetite films at 24-80°C

    K. Nishimura, Y. Kitamoto, M. Abe

    Digests of the Intermag Conference   1999

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  • Intergranular coupling and activation volume of Co ferrite thin films with high coercivity above 3 kOe

    Y. Kitamoto, F. Zhang, S. Kantake, F. Shirasaki, M. Abe, M. Naoe

    Digests of the Intermag Conference   1999

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    DOI: 10.1109/intmag.1999.837507

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  • Compact sputtering apparatus for depositing Co-Cr alloy thin films in magnetic disks Reviewed

    Y Kitamoto, M Abe, M Naoe

    VACUUM   51 ( 4 )   571 - 574   1998.12

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  • Preparation of NiZn Ferrite Films by Ultrasound-Enhanced Ferrite Plating

    YAJIMA H., NAKAYAMA Y., KITAMOTO Y., ABE M.

    Journal of the Magnetics Society of Japan   22 ( 4 )   473 - 476   1998.4

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    Polycrystalline films of spinel Fe3-x-yNixZnyO4 (x = 0−0.39, y = 0-0.3) were ferrite-plated from an aqueous solution (T = 75°C, pH = 6.8) of FeCl2 + NiCl2 + ZnCl2 to which an oxidizing solution of NaNO2 had been added. Low frequency (19.5 kHz, 600 W) ultrasound waves and high-frequency (1.6 MHz, 20 W) ultrasound waves were applied during plating. When the aqueous solutions were supplied intermittently, Fe3O4 (x = y = 0) films with a smooth surface were obtained only when low- and high-frequency ultrasound waves were applied simultaneously. On the other hand, supplying the aqueous solutions continuously facilitated formation of Fe3O4 films with a smooth surface during low-frequency sonication. The simultaneous sonication increased the solubility limit of Ni ions in Fe3-x-yNixZnyO4 films to x = 0.42 from the previous limit of x = 0.35 without sonication, though at a low deposition rate (4 nm/min).

    DOI: 10.3379/jmsjmag.22.473

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  • Enhancement of the Magneto-Optical Effect in Fe/SiO_2 and Co/SiO_2 Granular Films

    SEINO S., SATO I., MATSUMIYA H., SHIRASAKI F., KITAMOTO Y., ABE M.

    Journal of the Magnetics Society of Japan   22 ( 4 )   325 - 328   1998.4

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    We measured the Faraday rotation (FR) spectra (λ = 500-800 nm) in granular films of Ni/PVC (prepared by spin-coating polyvinyl chloride containing Ni fine powders of ∼20 nm diameter) and (Fe or Co)/SiO2 (prepared by RF-diode co-sputtering and annealed at 400-900°C). The FR spectrum in the Ni/PVC films was best-fitted by assuming that the volume fraction f of Ni is 0.27, though analysis resulted in f = 0.11, suggesting that the FR is enhanced; a possible explanation is "weak localization of light" in the granular structure. The FR in the Fe/SiO2 and Co/SiO2 granular films increased as the annealing temperature (Ta) was raised, reaching a maximum followed by a decrease. The maximum FR was, however, much smaller than that calculated for the films, probably because the size of the metal particles became comparable with the wavelength of light.

    DOI: 10.3379/jmsjmag.22.325

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  • Fine Grained Ni-Zn Ferrite-Plated Backlayers for Co-Cr-Ta Perpendicular Magnetic Recording Media

    KITAMOTO Yoshitaka, KANTAKE Shusuke, ABE Masanori

    Journal of the Magnetics Society of Japan   22 ( 1 )   S1_167 - 169   1998

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    &nbsp;&nbsp;Co-Cr-Ta perpendicular magnetic recording media with Ni-Zn ferrite backlayers are promising candidates to improve high frequency performance in extremely high linear density applications. Though ferrite plating facilitates to fabricate polycrystalline Ni-Zn ferrite films even at low temperature below 100&deg;C, the films have disadvantages of large grain size (200&sim;300 nm) and roughness (4&sim;5 nm). Such surface texture caused aggregating grains without clear magnetic isolations in Co-Cr-Ta layers deposited on them, resulting in low perpendicular coercivity Hc&perp; (1.3 kOe). These properties will lead poor recording density characteristics and high media noise. RF sputter-etching of the Ni-Zn ferrite backlayers was attempted in order to improve their surface texture. It reduced grain size (30&sim;50 nm), and increased Hc&perp; (3.0 kOe) in the Co-Cr-Ta layers, presumably through a reduction of surface roughness and a formation of many fine nodules on the Ni-Zn ferrite-plated backlayers, which play a role of nucleation sites for the Co-Cr-Ta grains.

    DOI: 10.3379/jmsjmag.22.S1_167

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  • Preparation of Perpendicular Anisotropic Co Ferrite Films below 100℃

    KITAMOTO Yoshitaka, KANTAKE Shusuke, SHIRASAKI Fumio, TAKAYA Shinichi, ABE Masanori

    ITE Technical Report   21 ( 71 )   9 - 13   1997.11

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    Perpendicular anisotropic Co_xFe_<3-x>O_4 films of 25〜200 nm in thickness were successfully obtained by the spin-spray ferrite-plating method at 90℃ for perpendicular magnetic recording media. Perpendicular coercivity H_<c⊥> of the Co_xFe_<3-x>O_4 took the maximum around at 0.5,and the value of H_<c⊥> was over 2000 Oe even at 25 nm in the film thickness. Due to optimizing a concentration of NaNO_2 in an oxidizing solution, in-plane coercivity H_<c//> decreased down to 300 Oe while H_<c⊥> was kept over 2000 Oe. Mossbauer analyses also show the films have excellent perpendicular magnetic anisotropy. The angular dependence of the coercivity shows the reversal of the magnetization takes place with a rotation mode, which is very close to Co-Cr sputter-deposited films.

    DOI: 10.11485/itetr.21.71.0_9

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  • Ultrasound enhanced ferrite plating; Bringing breakthrough in ferrite coating synthesized from aqueous solution Reviewed

    M Abe, Y Kitamoto, K Matsumoto, MJ Zhang, PL Li

    IEEE TRANSACTIONS ON MAGNETICS   33 ( 5 )   3649 - 3651   1997.9

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  • Ultrasound-Enhanced Ferrite Plating, a Novel Technique Applied to Ferrite-Encapsulation of Polymer Microspheres

    ZHANG M., KITAMOTO Y., HAIJIMA T., MATSUMOTO K., ABE M.

    Journal of the Magnetics Society of Japan   21 ( 3 )   135 - 138   1997.3

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    This is the first report on the combination of sonochemi-stry (the use of power ultrasound to stimulate chemical processes in liquids) with ferrite plating (a wet chemical method for synthesizing spinel ferrite films at low temper-ature from aqueous solution). By means of ultrasonic enhancement, an we successfully encapsulated polyacrylate microspheres whose average diameter was ∼0.25μm with continuous ferrite coating in an aqueous solution of FeC12 at 70°C. This broke the previous lower limit (∼0.3μm) on the size of the particles to be encapsulated;without application of the ultrasound waves, the ferrite coating became discontinuous or insular. The magnetic property of the continuous ferrite coating was better than those of the insular coating. The ferrite-encapsulated particles will greatly improve the performance of the enzyme immunoassay, which has been put to clinical use as a cancer test reagent with insular-ferrite-coated particles.

    DOI: 10.3379/jmsjmag.21.135

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    Other Link: http://dl.ndl.go.jp/info:ndljp/pid/10463375

  • Internal stress in ferrite plated thin films Reviewed

    Y Kitamoto, M Abe

    JOURNAL DE PHYSIQUE IV   7 ( C1 )   595 - 596   1997.3

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  • Fe3O4/CdS multi-layered films synthesized from aqueous solution Reviewed

    M Abe, T Miki, Y Kitamoto

    JOURNAL DE PHYSIQUE IV   7 ( C1 )   597 - 598   1997.3

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  • 20. 超音波励起フェライトメッキによる酸化物磁性膜の作製とその応用

    阿部 正紀, 北本 仁孝, 松本 圭司, 張 敏娟

    ソノケミストリー討論会講演論文集   5   51 - 53   1996

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    DOI: 10.20577/pamjss.5.0_51

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  • COERCIVITY CONTROL OF RF MAGNETRON SPUTTERED COCR FILMS BY EXTERNAL MAGNETIC-FIELD Reviewed

    Y UCHIYAMA, H SATO, Y KITAMOTO, U HWANG

    IEEE TRANSACTIONS ON MAGNETICS   26 ( 5 )   1617 - 1619   1990.9

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  • THE THICKNESS DEPENDENCE OF M-H CHARACTERISTICS OF CO-CR FILMS PREPARED BY FACING TARGETS SPUTTERING Reviewed

    S NAKAGAWA, Y KITAMOTO, M NAOE

    JOURNAL DE PHYSIQUE   49 ( C-8 )   1987 - 1988   1988.12

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  • STUDIES ON COERCIVITY IN CO-CR THIN-FILMS BY MEANS OF A MULTILAYER TECHNIQUE Reviewed

    S NAKAGAWA, M SUMIDE, Y KITAMOTO, Y NIIMURA, M NAOE

    JOURNAL OF APPLIED PHYSICS   63 ( 8 )   2911 - 2913   1988.4

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  • MULTILAYERED CO-CR FILMS WITH NON-MAGNETIC INTERMEDIATE LAYERS BY FTS SYSTEM Reviewed

    Y NIIMURA, Y KITAMOTO, S NAKAGAWA, M NAOE

    IEEE TRANSACTIONS ON MAGNETICS   23 ( 5 )   2464 - 2466   1987.9

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  • INFLUENCE OF FILM-GROWTH CONDITIONS ON C-AXIS ORIENTATION IN SPUTTERED CO-CR THIN-FILMS Reviewed

    Y NIIMURA, S NAKAGAWA, Y KITAMOTO, M NAOE

    JOURNAL OF APPLIED PHYSICS   61 ( 8 )   3152 - 3154   1987.4

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  • Crystallographic Orientation and Magnetic Behavior of Co-Cr Sputtered Thin Films in the Early Stage of Film Growth

    NAKAGAWA Shigeki, KITAMOTO Yoshitaka, SUMIDE Makoto, KUWASAKI Naoya, NIIMURA Yoshiro, NAOE Masahiko

    ITE Technical Report   11 ( 5 )   15 - 22   1987

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    DOI: 10.11485/tvtr.11.5_15

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Books

  • 第5版実験化学講座28-ナノテクノロジーの化学-(分担)

    丸善  2005 

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  • Carbon-Free Connected Nanoparticle Catalyst for Enhanced Oxygen Reduction Activity and Durability in Polymer Electrolyte Fuel Cells Reviewed

    Hidenori Kuroki, Takanori Tamaki, Masashi Matsumoto, Masazumi Arao, Yohei Takahashi, Hideto Imai, Yoshitaka Kitamoto, Takeo Yamaguchi

    2018.6

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  • The effect of electrolyte concentration on silicon nanoparticles prepared by laser ablation in liquid Reviewed

    Pattarin Chewchinda, Yoshitaka Kitamoto, Hiroshi Funakubo, Michikazu Hara, Osamu Odawara, Hiroyuki Wada

    2015.5

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  • 光音響イメージング用造影剤の作製と評価 Reviewed

    五十嵐 傑, 口丸 高弘, 張 茹芝, 北本 仁孝, 朝日 剛, 近藤 科江, 小田原 修, 和田裕之

    2015.3

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  • 種々の基板に成長したCo/Pd結晶性多層膜の光誘起磁化歳差運動 Reviewed

    高橋 克典, 西沢望, 西林 一彦, 松田 喬, 岩崎 大和, 北本 仁孝, 宗片 比呂夫

    予稿集   p. 09 - 061   2015.3

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  • Initial growth process of a Co layer on a Pd surface Reviewed

    Nozomi Nishizawa, YOSHITAKA KITAMOTO, Hiro MUNEKATA

    Abstracts book   p. 367   2014.11

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  • Fabrication of Langmuir-Blodgett Film of Surgace-Modefied ZnO Prepared by Solution Process Reviewed

    Yuhei Hasuike, Yoshitaka Kitamoto, Masahiko Hara, Osamu Odawara, Hiroyuki Wada

    2014.8

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  • 磁性ナノ粒子集積体の創製とデバイスへの応用 (特集 ナノ粒子創製と応用の最前線)

    北本 仁孝, 渕上 輝顕, 並木 禎尚

    ケミカルエンジニヤリング = Chemical engineering   59 ( 5 )   333 - 338   2014.5

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  • Detection of photo-induced ferromagnetic resonance in Co/Pd multilayers with oblique incidence angles Reviewed

    Junichi Saeki, Kazuhiro Nishibayashi, Takashi Matsuda, YOSHITAKA KITAMOTO, Hiro MUNEKATA

    p. 10 - 109   2014.3

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  • ポリビニルピロリドンを用いた光感受性物質を含有するシリカ修飾Y2O3:Er,Ybナノ粒子の合成と評価子 Reviewed

    藤井 邦生, 池畑 友裕, 北本 仁孝, 小田原 修, 和田 裕之

    2014

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  • Incidence angle and polarization dependence of photo-induced FMR in Co/Pd multilayers Reviewed

    J. Saeki, K. Nishibayashi, T. Matsuda, Y. Kitamoto, H. Munekata

    2013.12

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  • ポリビニルピロリドンを用いたアップコンバージョンナノ粒子Y2O3:Er,Ybのシリカコーティングとその光学特性 Reviewed

    藤井邦生, 北本仁孝, 原正彦, 小田原修, 和田裕之

    2013.9

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  • Pulsed optical excitation of ordered spin systems in the weak excitation regime Reviewed

    Hiro MUNEKATA, Takashi Matsuda, Kazuhiro Nishibayashi, YOSHITAKA KITAMOTO, Nozomi Nishizawa

    Abstract booklet   p. 6613 - 69   2013.8

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  • Synthesis of silica-coated upconversion nanoparticles Y2O3:Er,Yb by using polyvinylpyrrolidone Reviewed

    Kunio Fujii, Teruaki Fuchigami, Yoshitaka Kitamoto, Masahiko Hara, Osamu Odawara, Hiroyuki Wada

    2013.3

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  • Co/Pd多層膜における磁化の光誘起才差運動の励起光入射角度依存性 Reviewed

    佐伯 潤一, 西林 一彦, 山本 康介, 松田 喬, 北本 仁孝, 宗片 比呂夫

    予稿集   p. 10 - 093   2013.3

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  • Co/Pd多層膜における磁化の弱励起光誘起才差運動 Reviewed

    山本 康介, 松田 喬, 西林 一彦, 北本 仁孝, 宗片 比呂夫

    予稿集   p. 10 - 089   2013.3

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  • Low-power photo-induced precession of magnetization in ultra-thin Co/Pd multilayer films Reviewed

    K. Yamamoto, T. Matsuda, K. Nishibayashi, Y. Kitamoto, H. Munekata

    IEEE Transactions on Magnetics   49 ( 7 )   3155 - 3158   2013

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  • Fabrication of Iron Oxide Network Shell Particles and Their Application for Non-linear Magnetic Sensing

    ( 34 )   71 - 77   2013

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  • Preparation of Y <inf>2</inf> O <inf>3</inf> :Er,Yb nanoparticles by laser ablation in liquid Reviewed

    Takashi Nunokawa, Yuji Onodera, Masahiko Hara, Yoshitaka Kitamoto, Osamu Odawara, Hiroyuki Wada

    Applied Surface Science   261   118 - 122   2012.11

  • Photo-indeed precession of magnetization in [Co/Pd]5 multilayers with various magnetic anisotropy Reviewed

    K. Yamamoto, K. Nishibayashi, T. Matsuda, Y. Kitamoto, H. Munekata

    Abstract booklet   p. 439   2012.10

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  • Silicon Nanoparticles Prepared by Pulsed Laser Ablation in Liquid Reviewed

    Pattarin Chewchinda, Yoshitaka Kitamoto, Osamu Odawara, Hiroyuki Wada

    2012.9

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  • Magnetically-Guided Drug Delivery System using Magnetic Capsules composed of Nanometer-thick Shell

    KITAMOTO Yoshitaka, FUCHIGAMI Teruaki, NAKAGAWA Masaru, NAMIKI Yoshihisa

    2012 ( 70 )   27 - 31   2012.8

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  • 液中レーザーアブレーションによるY3Al5O12:Ceナノ蛍光体の作製 Reviewed

    鶴岡仙之, 片桐隆雄, 笹川崇男, 北本仁孝, 中村一隆, 山崎陽太郎, 小田原修, 山元明, 和田裕之

    電気化学会第79回大会   2012.3

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  • Sr2MgSi2O7:Eu,Dyナノ粒子のシリカ修飾と光学特性の評価 Reviewed

    石崎美佳, 渕上 輝顕, 片桐 隆雄, 北本 仁孝, 笹川 崇男, 山崎 陽太郎, 小田原 修, 和田 裕之

    電気化学会第79回大会   2012.3

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  • 液中レーザーアブレーションによるシリコンナノ粒子の作製と評価 Reviewed

    小林 宏輝, Pattarin Chewchinda, 北本 仁孝, 中村 一隆, 小田原 修, 和田 裕之

    第12回レーザー学会東京支部研究会, 電気学会 光・量子デバイス技術研究会   2012.3

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  • 液中レーザーアブレーション法により作製したY2O3:Er,Ybナノ粒子の光学特性 Reviewed

    小野寺 裕司, 布川 貴史, 北本仁孝, 原 正彦, 山崎 陽太郎, 中村 一隆, 小田原 修, 和田 裕之

    第59回 応用物理学関係連合講演会   2012.3

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  • Optical Properties of Silica-coated Sr2MgSi2O7:Eu,Dy Nanoparticles Prepared by Laser Ablation in Liquid Reviewed

    Mika Ishizaki, Teruaki Fuchigami, Yoshitaka Kitamoto, Osamu Odawara, Hiroyuki Wada

    Photoluminescence in Rare Earths: Photonic Materials and Devices (PRE'12)   2012.3

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  • 熱分解法を用いたY2O3:Er,Ybナノ粒子の合成 Reviewed

    藤井邦生, グバレビッチ アンナ, 北本仁孝, 原正彦, 山崎陽太郎, 小田原修, 和田裕之

    第59回 応用物理学関係連合講演会   2012.3

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  • Preparation of Silicon Nanoparticles by Laser Ablation in Liquid Reviewed

    Pattarin Chewchinda, Hiroki Kobayashi, Yoshitaka Kitamoto, Yohtaro Yamazaki, Osamu Odawara, Hiroyuki Wada

    2012.3

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  • [Co/Pd] 多層膜構造の作製と光励起によるスピンダイナミクスの評価 Reviewed

    山本康介, 西林一彦, 北本仁孝, 宗片比呂夫

    予稿集   p. 10 - 018   2012.3

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  • Preparation and Optical Properties of Rare Earth Doped Y2O3 Nanoparticles Synthesized by Thermal Decomposition with Oleic Acid Reviewed

    N. Takahashi, A. Gubarevich, J. Sakurai, S. Hata, T. Tsuge, Y. Kitamoto, Y. Yamazaki, O. Odawara, H. Wada

    ADVANCED TEXTILE MATERIALS, PTS 1-3   332-334   1974 - 1978   2011

  • 21pPSB-66 Anomalous Magnetic Property at Low Temperature of FePt Nanoparticles Protected by Polymer

    Iwamoto Takashi, Kitamoto Yoshitaka, Toshima Naoki

    Meeting abstracts of the Physical Society of Japan   62 ( 2 )   448 - 448   2007.8

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  • Effect of surfactant on syntheses of Fe-Pt nanoparticles

    YAMAMOTO Teruki, KITAMOTO Yoshitaka

    2006 ( 1 )   1 - 4   2006.11

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  • Crystallization process of amorphous CoFeB film in CoFeB/MgO/CoFeB magnetic tunnel junctions

    TAKEUCHI Takashi, GENSEKI Sou, KITAMOTO Yoshitaka, TSUNEKAWA Koji, NAGAMINE Yoshinori, DJAYAPRAWIRA David D., HOSHI Youichi

    2006 ( 1 )   17 - 20   2006.11

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  • Domain Structure and Magnetotransport Properties in (Ga,Mn)As Wires

    KOIZUMI Gaku, KONDO Tsuyoshi, NOMURA Kenta, KITAMOTO Yoshitaka, MUNEKATA Hiro

    2006 ( 1 )   21 - 24   2006.11

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  • Magnetic Properties of L1_0 Fe-Ni-Pt Films for Heat Assisted Magnetic Recording

    KANEKO Masahiko, SUEKI Kengo, KITAMOTO Yoshitaka

    151   33 - 38   2006.11

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  • Fabrication of Fe-C soft magnetic thin films using facing-targets sputtering method

    Yoshitaka Kitamoto, Hiroyuki Tagami, Kyung Ku Choi, Yohtaro Yamazaki

    Proceedings - Electrochemical Society   PV 2004-23   426 - 432   2006

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  • Domain structure and magnetotransport properties in (Ga,Mn)As wires

    G. Koizumi, T. Kondo, K. Nomura, Y. Kitamoto, H. Munekata

    Physica Status Solidi (C) Current Topics in Solid State Physics   3 ( 12 )   4090 - 4093   2006

  • Fabrication of Fe-Co-C thin films using facing targets sputtering method

    Goro Kiyota, Yoshitaka Kitamoto, Yohtaro Yamazaki

    Electrochimica Acta   51 ( 5 )   921 - 923   2005.11

  • Surface treatment of ferromagnetic nanoparticle-assembly by UV irradiation with ozone

    Mu Pei Chen, Kazuya Kuroishi, Yoshitaka Kitamoto

    Electrochimica Acta   51 ( 5 )   860 - 863   2005.11

  • Magnetotransport measurement of (Ga,Mn)As epilayers with low-temperature annealing

    H. Kato, K. Hamaya, Y. Kitamoto, T. Taniyama, H. Munekata

    Electrochimica Acta   51 ( 5 )   1004 - 1007   2005.11

  • Direct synthesis of L1<inf>0</inf> type Fe-Pt nanoparticles using microwave-polyol method

    Rumiko Minami, Yoshitaka Kitamoto, Tsukasa Chikata, Shunsaku Kato

    Electrochimica Acta   51 ( 5 )   864 - 866   2005.11

  • Surface treatment of ferromagnetic nanoparticle-assembly by UV irradiation with ozone

    Mu-Pei Chen, Kazuya Kuroishi, Yoshitaka Kitamoto

    Electrochimica Acta   51 ( 5 )   860 - 863   2005.11

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  • Fabrication of nanoparticle-assembly assisted by fatty-acid molecules

    Kazuya Kuroishi, Mu Pei Chen, Yoshitaka Kitamoto, Takahiro Seki

    Electrochimica Acta   51 ( 5 )   867 - 869   2005.11

  • Fabrication of Fe-Co-C thin films using facing targets sputtering method

    G Kiyota, Y Kitamoto, Y Yamazaki

    ELECTROCHIMICA ACTA   51 ( 5 )   921 - 923   2005.11

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  • Direct synthesis of L1(0) type Fe-Pt nanoparticles using microwave-polyol method

    R Minami, Y Kitamoto, T Chikata, S Kato

    ELECTROCHIMICA ACTA   51 ( 5 )   864 - 866   2005.11

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  • Fabrication of nanoparticle-assembly assisted by fatty-acid molecules

    K Kuroishi, MP Chen, Y Kitamoto, T Seki

    ELECTROCHIMICA ACTA   51 ( 5 )   867 - 869   2005.11

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  • Evaluation of atomic arrangement in Fe-Pt nanoparticles by x-ray diffraction and Mossbauer spectroscopy

    SAKUMA Hiroshi, TANIYAMA Tomoyasu, KITAMOTO Yoshitaka, ISHII Kiyoshi, YAMAZAKI Yohtaro

    2005 ( 50 )   59 - 64   2005.7

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  • CoZrNb/Fe-C discontinuous multilayer films for GHz applications

    KK Choi, T Murase, Y Fujikawa, Y Kitamoto, Y Yamazaki

    NINTH INTERNATIONAL CONFERENCE ON FERRITES (ICF-9)   171 - 176   2005

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  • Structure and Magnetic Properties of Partially Ordered Fe-Pt Nanoparticles Synthesized by Chemical Method

    KITAMOTO Yoshitaka, MINAMI Rumiko, CHIKATA Tsukasa, KATO Syunsaku, NISHIO Hiroaki, YAMAMOTO Hiroshi

    IEICE technical report. Magnetic recording   104 ( 408 )   1 - 4   2004.11

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    Partially ordered Fe-Pt nanoparticles are synthesized by a polyol method with microwave irradiation at 250℃. Whereas the ordered Fe-Pt nanoparticles exhibit coercivity of 3.4 kOe and anisotropy field H_k^<Wr>, of 83 kOe at room temperature, an evaluation of anisotropy field distribution reveals that many particles with low anisotropy field are included. Mossbauer spectroscopy shows 60 % of Fe atoms in the partially ordered Fe-Pt nanoparticles are in the L1_0 ordered structure.

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  • 12aPS-26 Synthesis and Magnetic Properties of Co Nanowhiskers

    Iwamoto Takashi, Kitamoto Yoshitaka, Yamazaki Yohtaro, Toshima Naoki

    Meeting abstracts of the Physical Society of Japan   59 ( 2 )   345 - 345   2004.8

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  • 12aPS-34 Spin polarized electron transport across Fe wire/GaAs

    Wada E, Taniyama T., Kitamoto Y.

    Meeting abstracts of the Physical Society of Japan   59 ( 2 )   347 - 347   2004.8

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  • 27aPS-41 Magnetotransport measurements of the annealed (Ga,Mn)As epilayer

    Kato H, Hamaya K, Taniyama T, Kitamoto Y, Munekata H

    Meeting abstracts of the Physical Society of Japan   59 ( 1 )   444 - 444   2004.3

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  • Structure and Magnetic Properties of Partially Ordered Fe-Pt Nanoparticles Synthesized by Chemical Method

    KITAMOTO Yoshitaka, MINAMI Rumiko, CHIKATA Tsukasa, KATO Syunsaku, NISHIO Hiroaki, YAMAMOTO Hiroshi

    ITE technical report   28 ( 64 )   1 - 4   2004

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  • (Ga, Mn)As薄膜における[110]一軸磁気異方性とキャリア濃度の関係

    濱屋宏平, 谷山智康, 北本仁孝, 守谷頼, 大岩顕, 宗片比呂夫

    日本物理学会第59回年次大会   2004

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  • 目下話題の磁気記録材料 「化学合成によるFePt規則合金微粒子」

    北本仁孝

    (社)未踏科学技術協会・磁性材料研究会21・第4回講演会   2004

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  • Fe-Ptナノ粒子の構造と磁性

    北本仁孝, 佐久間洋志, 山崎陽太郎, 西尾博明, 山元洋

    (社)粉体粉末冶金協会 平成16年度春季大会   2004

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  • (Ga,Mn)As薄膜におけるアニール効果の磁気伝導評価

    加藤裕明, 浜屋宏平, 谷山智康, 北本仁孝, 宗片比呂夫

    日本物理学会第59回年次大会   2004

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  • カーボンコートしたFe-Ptナノ粒子集積膜の微細構造と磁気特性

    陳穆霈, 黒石和哉, 北本仁孝

    第28回日本応用磁気学会学術講演会概要   2004

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  • (Ga,Mn)As薄膜の交流磁化率と磁気異方性

    濱屋宏平, 谷山智康, 北本仁孝, 宗片比呂夫

    日本物理学会2004年秋季大会   2004

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  • マイクロ波照射ポリオール還元法により合成したFe-Ptナノ粒子の磁気異方性

    南瑠美子, 北本仁孝, 近田司, 加藤俊作

    第28回日本応用磁気学会学術講演会概要   2004

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  • 飽和脂肪酸分子を混合して作製したFe-Ptナノ粒子配列膜

    黒石和哉, 陳穆霈, 北本仁孝, 関隆広

    第28回日本応用磁気学会学術講演会概要   2004

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  • Activation volume and magnetization reversal of assembled-films composed of magnetically isolated Fe-Pt nanoparticles

    M. P. Chen, Y. Kitamoto

    The 49th Annual Conference on Magnetism & Magnetic Materials   2004

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  • High-Field Torque Measurement of FePt Nanoparticles

    H. Sakuma, H. Nishio, Y. Kitamoto, Y, Yamazaki, H. Yamamoto

    Trans. Magn. Soc. Japan   4 ( 1 )   24 - 27   2004

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    Two methods using torque measurement in magnetic fields of up to 90 kOe were applied to evaluating the magnetocrystalline anisotropy of FePt nanoparticle samples with various order parameters. The maximum anisotropy field in the samples was obtained from the rotational hysteresis loss measurement. It was shown that the maximum anisotropy field monotonically increases with the order parameter. The magnetic anisotropy constant corresponding to the maximum anisotropy field of the sample with an order parameter of 0.96 is 4.4×107erg/cm3. The anisotropy field distribution was also obtained by using Flanders and Shtrikman's method. Thermal relaxation of magnetization was, however, superimposed on the anisotropy field distribution at 300 K.

    DOI: 10.3379/tmjpn2001.4.24

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  • ラングミュア・ブロジェット法によるFe-Ptナノ粒子集積膜の作製

    黒石和哉, 伊藤宏樹, 北本仁孝

    科学技術振興調整費先導的研究等の推進「ナノ界面制御による磁気記録材料の創製」公開シンポジウム   2004

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  • Magnetic Nanoparticles and Their Self-assembly

    Yoshitaka Kitamoto

    AUN/SEED-Net Field-Wise Seminar on NANOMATERIALS-Recent Advances, Perspective and Chanllenges KEYNOTE LECTURE   2004

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  • Fe-Coスパッタ薄膜へのカーボン添加効果

    清田吾朗, 北本仁孝, 山崎陽太郎

    第28回日本応用磁気学会学術講演会概要   2004

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  • Fe-Pt粒子の規則度と磁気異方性

    北本仁孝, 佐久間洋志, 谷山智康, 山崎陽太郎, 西尾博明, 山元洋

    科学技術振興調整費先導的研究等の推進「ナノ界面制御による磁気記録材料の創製」公開シンポジウム   2004

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  • Synthesis of Fe-Pt Ordered Alloy Nanoparticles by Microwave-assisted Polyol Method

    Rumiko Minami, Yoshitaka Kitamoto, Tsukasa Chikata, Shunsaku. Kato

    International Symposium on Microwave Science and Its Application to Related Fields (MICROWAVE 2004)   2004

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  • Annealing-Temperature Dependent Magnetic Behaviorof FePt Nanoparticle-Assemblies Deposited by Langmuir-Blodgett Method

    M. Chen, Y. Kitamoto

    9th Joint MMM/Intermag Conference   2004

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  • Influence of Chemical Conditions in Fabrication of Bi-YIG Precursor on Morphological and Magnto-Optical Response of Its Particulate Film

    C. S. Kuroda, T. Taniyama, Y. Kitamoto, K, Uchida F, Ikazaki Y. Yamazaki

    9th International Conference on Ferrites   2004

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  • Mossbauer Study of Atomic Ordering in FePt Nanoparticles

    Y. Kitamoto, H. Sakuma, Y. Yamazaki

    9th International Conference on Ferrites   2004

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  • Magnetic confuguration of (Ga,Mn)As wires controlled by hole concentration or temerature

    K. Hamaya, T. Taniyama, Y. Kitamoto, Y. Yamazaki, R. Moriya, A. Oiwa, H. Munekata

    The 10th Physics and Application of Spin-Related Phenomena in Semiconductors   2004

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  • Cation Order Dependent Magntization and Magnetoresistance of Double Perovskite Sr2FeMoO6

    H. Sakuma, T. Taniyama, Y. Kitamoto, Y. Yamazaki

    9th International Conference on Ferrites   2004

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  • Magnetic Nanoparticles and Their Self-assembly

    Yoshitaka Kitamoto

    AUN/SEED-Net Field-Wise Seminar on NANOMATERIALS-Recent Advances, Perspective and Chanllenges KEYNOTE LECTURE   2004

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  • Synthesis of Fe-Pt Ordered Alloy Nanoparticles by Microwave-assisted Polyol Method

    Rumiko Minami, Yoshitaka Kitamoto, Tsukasa Chikata, Shunsaku. Kato

    International Symposium on Microwave Science and Its Application to Related Fields (MICROWAVE 2004)   2004

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  • Annealing-Temperature Dependent Magnetic Behaviorof FePt Nanoparticle-Assemblies Deposited by Langmuir-Blodgett Method

    M. Chen, Y. Kitamoto

    9th Joint MMM/Intermag Conference   2004

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  • Influence of Chemical Conditions in Fabrication of Bi-YIG Precursor on Morphological and Magnto-Optical Response of Its Particulate Film

    C. S. Kuroda, T. Taniyama, Y. Kitamoto, K, Uchida F, Ikazaki Y. Yamazaki

    9th International Conference on Ferrites   2004

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  • Mossbauer Study of Atomic Ordering in FePt Nanoparticles

    Y. Kitamoto, H. Sakuma, Y. Yamazaki

    9th International Conference on Ferrites   2004

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  • CoZrNb/Fe-C Discontinuous Multilayer Films for GHz Applications

    K. Choi, T, Murase, Y. Fujikawa, Y. Kitamoto, Y. Yamazaki

    9th International Conference on Ferrites   2004

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  • Cation Order Dependent Magntization and Magnetoresistance of Double Perovskite Sr2FeMoO6

    H. Sakuma, T. Taniyama, Y. Kitamoto, Y. Yamazaki

    9th International Conference on Ferrites   2004

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  • Fabrication of Fe-C soft magnetic thin films by facing-targets sputtering method

    Yoshitaka Kitamoto, Hiroyuki Tagami Kyung-Ku Choi Yohtaro Yamazaki

    5th International Symposium on Electrochemical Micro & Nnano System Technologies   2004

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  • Magnetic confuguration of (Ga,Mn)As wires controlled by hole concentration or temerature

    K. Hamaya, T. Taniyama, Y. Kitamoto, Y. Yamazaki, R. Moriya, A. Oiwa, H. Munekata

    The 10th Physics and Application of Spin-Related Phenomena in Semiconductors   2004

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  • High-Field Torque Measurement of FePt Nanoparticles

    SAKUMA H., NISHIO H., KITAMOTO Y., YAMAZAKI Y., YAMAMOTO H.

    Journal of the Magnetics Society of Japan   4 ( 1 )   24 - 27   2004

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    Two methods using torque measurement in magnetic fields of up to 90 kOe were applied to evaluating the magnetocrystalline anisotropy of FePt nanoparticle samples with various order parameters. The maximum anisotropy field in the samples was obtained from the rotational hysteresis loss measurement. It was shown that the maximum anisotropy field monotonically increases with the order parameter. The magnetic anisotropy constant corresponding to the maximum anisotropy field of the sample with an order parameter of 0.96 is 4.4×107erg/cm3. The anisotropy field distribution was also obtained by using Flanders and Shtrikman's method. Thermal relaxation of magnetization was, however, superimposed on the anisotropy field distribution at 300 K.

    DOI: 10.3379/tmjpn2001.4.24

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  • Control of Magnetic Anisotropy and Magnetotransport in Epitaxial Micropatterned (Ga,Mn)As Wire Structures

    K. Hamaya, R. Moriya, A. Oiwa, T. Taniyama, Y. Kitamoto, H. Munekata

    IEEE Transactions on Magnetics   39 ( 5 )   2785 - 2787   2003.9

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  • Effect of atomic ordering on magnetization decay and activation volume of FePt nanoparticles

    H Sakuma, H Nishio, Y Kitamoto, Y Yamazaki, H Yamamoto

    IEEE TRANSACTIONS ON MAGNETICS   39 ( 5 )   2758 - 2760   2003.9

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  • Magnetoresistance and magnetic anisotropy of (Ga, Mn) As wires

    Hamaya K., Taniyama T., Kitamoto Y., Moriya R., Munakata H.

    Meeting abstracts of the Physical Society of Japan   58 ( 2 )   392 - 392   2003.8

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  • Anomalous hall resistivity due to grain boundary in manganite thin films

    T. Taniyama, K. Hamaya, Y. Kitamoto, Y. Yamazaki

    Journal of Applied Physics   93 ( 10 )   8107 - 8109   2003.5

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    DOI: 10.1063/1.1543865

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  • Anomalous Hall resistivity due to grain boundary in manganite thin films

    T Taniyama, K Hamaya, Y Kitamoto, Y Yamazaki

    JOURNAL OF APPLIED PHYSICS   93 ( 10 )   8107 - 8109   2003.5

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  • Cation order and magnetic properties of double perovskite Sr2FeMoO6

    H Sakuma, T Taniyama, Y Kitamoto, Y Yamazaki

    JOURNAL OF APPLIED PHYSICS   93 ( 5 )   2816 - 2819   2003.3

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  • Asymmetric transport due to spin injection into a Kondo alloy

    T Taniyama, N Fujiwara, Y Kitamoto, Y Yamazaki

    PHYSICAL REVIEW LETTERS   90 ( 1 )   016601_1-4   2003.1

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  • High-frequency Properties of CoZrNb/Fe-C Multilayer Films

    K.-K. Choi, T, Murase T, Yokoshima T. Osaka, Y. Kitamoto, Y. Yamazaki

    Trans. Magn. Soc. Japan   3 ( 2 )   55 - 58   2003

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    High permeability of -500 up to the GHz frequency range was observed in a CoZrNb/Fe-C multilayer film deposited by using a facing-target sputtering apparatus at room temperature. It was found that the Fe-C layer played a key role in increasing the saturation magnetization and the anisotropy field of the multilayer film sufficiently to raise the ferromagnetic resonance frequency beyond 2.0GHz. The multilayer film was soft magnetic when the thickness of the Fe-C layer was 5-50 nm. The Fe-C layer exhibited a columnar growth feature, and the aspect ratio of the column increased with increasing the Fe-C layer thickness. Magnetic anisotropy perpendicular to the film plane appeared in multilayer films with Fe-C layer thicknesses of -80nm and above.

    DOI: 10.3379/tmjpn2001.3.55

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  • Magnetotransport study of temperature dependent magnetic anisotropy in a (Ga,Mn)As epilayer

    K.Hamaya, T.Taniyama, Y.Kitamoto, R.Moriya, H.Munekata

    J.Appl.Phys.   94 ( 12 )   7657 - 7661   2003

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  • Control of Magnetic Features in Epitaxial Micro-Patterned (Ga,Mn)As Wire Structures

    K. HAMAYA, R, MORIYA A, OIWA T, TANIYAMA Y, KITAMOTO, H. MUNEKATA

    IEEE Trans. on Magn.   39 ( 5 )   2785 - 2787   2003

  • (Ga,Mn)As薄膜における面内磁気抵抗の温度依存性

    濱屋宏平, 守谷頼, 谷山智康, 北本仁孝, 宗片比呂夫

    第27回日本応用磁気学会学術講演概要集   2003

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  • High-frequency Properties of CoZrNb/Fe-C Multilayer Films

    CHOI K.-K., MURASE T., YOKOSHIMA T., OSAKA T., KITAMOTO Y., YAMAZAKI Y.

    Journal of the Magnetics Society of Japan   3 ( 2 )   55 - 58   2003

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    Language:English   Publisher:The Magnetics Society of Japan (MSJ)  

    High permeability of -500 up to the GHz frequency range was observed in a CoZrNb/Fe-C multilayer film deposited by using a facing-target sputtering apparatus at room temperature. It was found that the Fe-C layer played a key role in increasing the saturation magnetization and the anisotropy field of the multilayer film sufficiently to raise the ferromagnetic resonance frequency beyond 2.0GHz. The multilayer film was soft magnetic when the thickness of the Fe-C layer was 5-50 nm. The Fe-C layer exhibited a columnar growth feature, and the aspect ratio of the column increased with increasing the Fe-C layer thickness. Magnetic anisotropy perpendicular to the film plane appeared in multilayer films with Fe-C layer thicknesses of -80nm and above.

    DOI: 10.3379/tmjpn2001.3.55

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  • (Ga,Mn)As薄膜における磁気異方性のアニール効果

    加藤裕明, 濱屋宏平, 守谷頼, 谷山智康, 北本仁孝, 宗片比呂夫

    第27回日本応用磁気学会学術講演会概要集   2003

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  • Cation Order and Magnetic Properties of Double Perovskite Sr2FeMoO6

    Hiroshi Sakuma, Tomoyasu Taniyama Yoshitaka Kitamoto Yohtaro Yamazaki

    J. Appl. Phys.   93 ( 5 )   2816 - 2819   2003

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  • (Ga,Mn)As細線の異方的磁気輸送特性

    濱屋宏平, 守谷頼, 大岩顕, 谷山智康, 北本仁孝, 宗片比呂夫

    第50回応用物理学関係連合講演会   2003

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  • FePt nanoparticle-assembly for magnetic recording media

    Y Kitamoto, H Sakuma, A Jogo, T Taniyama, Y Yamazaki, H Nishio, H Yamamoto

    MAGNETIC MATERIALS, PROCESSES, AND DEVICES VII AND ELECTRODEPOSITION OF ALLOYS, PROCEEDINGS   2002 ( 27 )   483 - 490   2003

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    Web of Science

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  • FePt微粒子薄膜のLangmuir-Blodgett法による作製

    伊藤宏樹, 黒石和哉, 陳穆霈, 北本仁孝

    粉体粉末冶金協会講演概要集平成15年度秋季大会   2003

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  • 微細加工を用いた(Ga,Mn)Asの磁気構造

    濱屋宏平, 守谷頼, 谷山智康, 北本仁孝, 大岩顕, 宗片比呂夫

    第64回応用物理学会学術講演会   2003

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  • FePtナノ粒子粉末の強磁場トルク測定

    佐久間洋志, 西尾博明, 北本仁孝, 山崎陽太郎, 山元洋

    第27回日本応用磁気学会学術講演概要集   2003

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  • 熱処理温度によるFePt微粒子集積膜の構造及び磁気特性の変化

    陳穆霈, 北本仁孝, 山崎陽太郎

    粉体粉末冶金協会講演概要集平成15年度秋季大会   2003

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  • 高周波用CoZrNb/Fe-C積層膜

    崔京九, 村瀬琢, 藤川佳則, 北本仁孝, 山崎陽太郎

    第27回日本応用磁気学会学術講演概要集   2003

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  • 対向ターゲット式スパッタリング法によるFe-C軟磁性薄膜の作製

    田上裕之, 崔京九, 北本仁孝, 山崎陽太郎

    第27回日本応用磁気学会学術講演概要集   2003

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  • Open the Gate of the Academic Ivory Tower!!!

    KITAMOTO Yoshitaka

    53 ( 11 )   705 - 705   2002.11

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  • Change in resistance of CuFe wires induced by spin injection

    T Taniyama, N Fujiwara, Y Kitamoto, Y Yamazaki

    IEEE TRANSACTIONS ON MAGNETICS   38 ( 5 )   2872 - 2874   2002.9

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  • Bi-YIG nanoparticle and plastic hybridized magnetooptical material

    TY Kim, T Hirano, Y Kitamoto, T Hasegawa, H Koinuma, Y Yamazaki

    IEEE TRANSACTIONS ON MAGNETICS   38 ( 5 )   3240 - 3242   2002.9

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  • Interlayer coupling in (In,Mn)As/InAs/(In,Mn)As magnetic semiconductor trilayer structures

    S Yanagi, H Munekata, Y Kitamoto, A Oiwa, T Slupinski

    JOURNAL OF APPLIED PHYSICS   91 ( 10 )   7902 - 7904   2002.5

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  • Magneto-optical properties and morphology of particulate film consisting of Bi-YIG coprecipitated particles

    CS Kuroda, T Taniyama, Y Kitamoto, Y Yamazaki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   241 ( 2-3 )   201 - 206   2002.3

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  • FePt Nanoparticle-assembly for Magnetic Recording Media

    Yoshitaka Kitamoto, Hiroshi Sakuma Arata Jogo Tomoyasu, Taniyama Yohtaro Yamazaki

    Electrochemical Society Meeting/7th International Symposium on Magnetic Materials, Processes and Devices   2002

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  • FePtナノ粒子の作製と磁気特性

    佐久間洋志, 城後新, 谷山智康, 北本仁孝, 山崎陽太郎

    (社〕粉体粉末冶金協会 平成14年度春季大会   2002

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  • 高密度磁気記録媒体用ナノ粒子の合成と集積膜

    佐久間洋志, 城後新, 谷山智康, 北本仁孝, 山崎陽太郎

    電気化学会春季講演会   2002

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  • 界面活性剤を添加して焼成した時のYIG微粒子結晶化への影響

    柿原康男, 高橋亮, 北本仁孝, 山崎陽太郎

    第26回日本応用磁気学会学術講演会   2002

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  • 溶液プロセスにより作製したFePt微粒子の磁気緩和

    佐久間洋志, 城後新, 西尾博明, 北本仁孝, 山崎陽太郎, 山元洋

    第26回日本応用磁気学会学術講演会   2002

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  • 共沈法によるBi-YIG微粒子合成における硫酸アンモニウム添加の効果

    高橋亮, 柿原康男, 北本仁孝, 山崎陽太郎

    (社〕粉体粉末冶金協会 平成14年度秋季大会   2002

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  • CoZrNb/Fe-C積層膜の高周波特性

    崔京九, 村瀬琢, 横島時彦, 逢坂哲弥, 北本仁孝, 山崎陽太郎

    第26回日本応用磁気学会学術講演会   2002

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  • Fabrication and self-assembling of FePt nanoparticles

    SAKUMA Hiroshi, JOGO Arata, TANIYAMA Tomoyasu, KITAMOTO Yoshitaka, YAMAZAKI Yohtaro

    ITE Technical Report   26 ( 38 )   25 - 28   2002

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    Language:Japanese   Publisher:The Institute of Image Information and Television Engineers  

    Nanoparticles of FePt were fabricated by two types of solution process. One is thermal decomposition and reduction of organometallic compounds in nonpolar solvent; the other is reduction of metal ions in reversed micelles. In either way, monodisperse FePt particles of about 3nm are formed. Self-assembly was observed in case of the particles fabricated by the former method, while in case of the latter method, self-assembly was not observed. The maximum diameter of particles in assembled film increased up to 1Onm by annealing.

    DOI: 10.11485/itetr.26.38.0_25

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  • FePtナノ粒子のウエットプロセスによる合成と集積薄膜

    佐久間洋志, 城後新, 谷山智康, 北本仁孝, 山崎陽太郎

    未来開拓学術研究推進事業「原子界面設計による高密度磁気記録デバイスの研究開発」プロジェクト公開シンポジウム・成果報告会   2002

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  • Magnetic Properties of FePt particles and their assembly-films

    KITAMOTO Yoshitaka, SAKUMA Hiroshi, ITOH Hiroki, YAMAZAKI Yohtaro, NISHIO Hiroaki, YAMAMOTO Hiroshi

    ITE Technical Report   26   29 - 32   2002

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    Nanparticles of FePt were fabricated by two types of solution process. One is thermal decomposition and reduction of organometallic compounds in an organic slovent, and the other is reduction of metl ions in reversed micelles based on an aqueous solutiion process. In either way, mondisperse FePt prticles of about 3nm are fourmed. Self-assembly was observed in case of the particles fabricated by the former method, while in case of the latter method, self-assembly was not observe. The maximum diameter of particles in assembled film increased up to 10nm by annealing. Magnetic evaluation in the from of powder showed that atomic ordering of Fe and Pt in L1_0 structure strongly influenced coercivity and magnetization decay.. It is necessary to improve the accuracy for magnetic measurements of very thin assembly-films since their magnetization is too small.

    DOI: 10.11485/itetr.26.71.0_29

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  • FePt Nanoparticle-assembly for Magnetic Recording Media

    Yoshitaka Kitamoto, Hiroshi Sakuma Arata Jogo Tomoyasu, Taniyama Yohtaro Yamazaki

    Electrochemical Society Meeting/7th International Symposium on Magnetic Materials, Processes and Devices   2002

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  • Crossober of magnetotransport process toward spin-polarized tunneling in manganite thin films

    T.Taniyama, N.Fujiwara, Y.Kitamoto, Y.Yamazaki

    Appl.Phys.Lett.   81 ( 24 )   4562 - 4564   2002

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  • Magnetic Properties of FePt Particles and Their Assembly-films

    Yoshitaka Kitamoto, Hiroshi Sakuma, Hiroki Itoh Yohtaro, Yamazaki, Hiroshi Yamamoto

    7th Asian Symposium on Information Storage Technology   26   29 - 32   2002

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    Language:English   Publisher:The Institute of Image Information and Television Engineers  

    Nanparticles of FePt were fabricated by two types of solution process. One is thermal decomposition and reduction of organometallic compounds in an organic slovent, and the other is reduction of metl ions in reversed micelles based on an aqueous solutiion process. In either way, mondisperse FePt prticles of about 3nm are fourmed. Self-assembly was observed in case of the particles fabricated by the former method, while in case of the latter method, self-assembly was not observe. The maximum diameter of particles in assembled film increased up to 10nm by annealing. Magnetic evaluation in the from of powder showed that atomic ordering of Fe and Pt in L1_0 structure strongly influenced coercivity and magnetization decay.. It is necessary to improve the accuracy for magnetic measurements of very thin assembly-films since their magnetization is too small.

    DOI: 10.11485/itetr.26.71.0_29

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  • Improvement in magneto-optical properties of Bi-YIG particulate films by reduction in particle size

    CS Kuroda, T Taniyama, Y Kitamoto, Y Yamazaki, T Hirano

    IEEE TRANSACTIONS ON MAGNETICS   37 ( 4 )   2432 - 2434   2001.7

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  • Improving Fine Structure of Co Ferrite Magnetic Thin Film by Ni Addition

    F. Zhang, Y. Kitamoto, M. Abe, M. Naoe

    Ferrite: Proceedings of The Eighth International Conference on Ferrites (ICF 8)   1073 - 1075   2001

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  • Magnetic and recording characteristics of Co-Ni ferrite recording layers on soft ferrite underlayers

    Fuchun Zhang Nobuhiro Matsushita Masanori Abe, Yoshitaka Kitamoto

    The 8th Joint MMM-Intermag Conference   2001

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  • 強磁性FePtナノ微粒子の逆ミセルによる作製

    城後新, 谷山智康, 北本仁孝, 山崎陽太郎

    第25回日本応用磁気学会学術講演会   2001

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  • Magnetic and Read/write Characteristics of CoNi Ferrite Perpendicular Recording Media with Soft Ferrite Underlayers

    Fuchun Zhang Nobuhiro Matsushita Masanori Abe, Yoshitaka Kitamoto

    International Conference on Materials for Advanced Technologies   2001

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  • フェライトめっき法によるマグネタイト薄膜の微細加工と電気的特性

    栗原淳旨, 谷山智康, 北本仁孝, 山崎陽太郎

    (社〕粉体粉末冶金協会 平成13年度秋季大会   2001

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  • Co/Cu(Fe)接合細線におけるスピン注入

    藤原直人, 谷山智康, 北本仁孝, 山崎陽太郎

    第25回日本応用磁気学会学術講演会   2001

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  • NiZn Ferrite Coating for Electrical Insulation of MnZn Ferrite Cores

    Y. Nakayama, H. Yajima, Y. Kitamoto, M. Abe

    Journal of the Korean Ceramic Society   38 ( 6 )   506 - 508   2001

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  • Magnetic and Mossbauer Study of Sr_2_FeMoO_6_ Partially Ordered Double Perovskite

    H. Sakuma, T. Taniyama, Y. Kitamoto, Y. Yamazaki

    Journal of the Magnetics Society of Japan   25 ( 4-2 )   731 - 734   2001

  • Magnetotransport and Mossbauer study of Fe3O4/gFe2O3 granular thin films

    T.Taniyama, Y.Kitamoto, Y.Yamazaki

    Journal of Applied Physics   89 ( 11,Pt.2 )   7693 - 7695   2001

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  • Magnetic Anisotropy of Co-substituted Bi-DyAllG Nanoparticles

    T.Y. Kim, T. Taniyama, Y. Kitamoto, Y. Yamazaki, Y.D. Hong

    Journal of the Japan Society of Powder and Powder Metallurgy   48 ( 8 )   710 - 714   2001

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    The magnetic properties of the superparamagnetic Co-substituted Bi-DyAJIG (BiDy2CoxAlyFe5-x-yO12: 0≤x≤0.2, 0≤y≤1.1) nanoparticles were investigated. On the basis of the magnetic data, it is inferred that the magnetic moments of Dy ions cant from those of the iron ions. The canting angle was estimated to be 53°, which is larger than that previously observed in the sputtered films. The reason of the canting is possibly the surface and/or size effect of the nano-size garnet particles. The Co substitution was found to be effective to increase the coercive-force of the nanoparticles for magnetic recording storage media. The bifurcation temperature of zero-field-cooled (ZFC) and field-cooled (FC) magnetizations is also increased by the Co substitution. The ZFC and FC magnetization curves for the BiDy2CoxAly, Fe5-x-yO12 nanoparticles suggest that Co substitution enhances magnetic anisotropy of the nanoparticles, which is in accordance with increase in coercive-force Hc.

    DOI: 10.2497/jjspm.48.710

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  • Magneto-optical properties of Bi-YIG particle-composite Films prepared by different coprecipitaion procedures

    T. Taniyama C, S. Kuroda, Y. Kitamoto, Y. Yamazaki

    J. Magn. Soc. Japan   25 ( 3-2 )   311 - 312   2001

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    Magneto-optical Bi-YIG particles are prepared by different coprecipitation procedures. The crystallite size of the particle increases with the heat treatment temperature. In spite of a similar crystallite size, the saturation magnetization is considerably different by the coprecipitation procedure. The Faraday rotation of the composite film with the mixture of epoxy and the Bi-YIG particles linearly increases with the saturation magnetization for the film with crystallites smaller than 30 nm, while that for the film with larger crystallites deviates from the linearity and exhibits a decrease in the Faraday rotation. These results can be interpreted based on the scattering of the probing light due to the morphology of the composite film. The presence of a magneto-optically inactive surface region of the crystallite is also discussed.

    DOI: 10.3379/jmsjmag.25.311

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  • perpendicular Magnetic Orientation of co-substituted Bi-DyAlIG Nanoparticles for Magneto-Optical Strage Media

    T.Y.Kim, Y.Yamazaki, Y.Kitamoto, Y.D.Hong

    161   2001

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  • NiZn Ferrite Coating for Electrical Insulation of MnZn Ferrite Cores

    Y. Nakayama, H. Yajima, Y. Kitamoto, M. Abe

    Journal of the Korean Ceramic Society   38 ( 6 )   506 - 508   2001

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  • Magnetic and Mossbauer Study of Sr_2_FeMoO_6_ Partially Ordered Double Perovskite

    H. Sakuma, T. Taniyama, Y. Kitamoto, Y. Yamazaki

    Journal of the Magnetics Society of Japan   25 ( 4-2 )   731 - 734   2001

  • Magnetic and Read/write Characteristics of CoNi Ferrite Perpendicular Recording Media with Soft Ferrite Underlayers

    Fuchun Zhang Nobuhiro Matsushita Masanori Abe, Yoshitaka Kitamoto

    International Conference on Materials for Advanced Technologies   2001

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  • Magnetic and recording characteristics of Co-Ni ferrite recording layers on soft ferrite underlayers

    Fuchun Zhang Nobuhiro Matsushita Masanori Abe, Yoshitaka Kitamoto

    The 8th Joint MMM-Intermag Conference   2001

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  • 多結晶La1-xSrMnO3薄膜における磁気伝導のアニール効果II

    濱屋宏平, 谷山智康, 北本仁孝, 山崎陽太郎

    第56回年次大会 日本物理学会講演概要集   354   2001

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  • Optimum Conditions for Preparing from Aqueous Solutions Co-Ni Ferrite Films for Perpendicular Magnetic Recording

    F. Zhang, Y. Kitamoto, M. Abe

    Ferrite: Proceedings of The Eighth International Conference on Ferrites (ICF 8)   1058 - 1060   2001

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  • ダブルペロブスカイト型酸化物Sr2FeMoO6のBサイトイオン配列と磁性

    佐久間洋志, 谷山智康, 北本仁孝, 山崎陽太郎

    第56回年次大会 日本物理学会講演概要集   389   2001

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  • Room Temperature Film Syntheses of Spinel Ferrites ((Fe, M)_3_O_4_, M=Fe, Co, Ni, and Zn) from Aqueous Solution

    K. Nishimura, N. Matsushita, Y. Kitamoto, M. Abe

    Ferrite: Proceedings of The Eighth International Conference on Ferrites (ICF 8)   615 - 617   2001

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  • Ferrite-plated Co_x_Fe_3-x_O_4_ Insulation Layers for Mn-Zn Ferrite Cores

    M. Sakai, Y. Nakayama, N. Matsushita, Y. Kitamoto, M. Abe

    Ferrite: Proceedings of The Eighth International Conference on Ferrites (ICF 8)   657 - 659   2001

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  • High-Density Magnetic Recording Application of Co Ferrite Thin Films Prepared by Ferrite-Plating Technique

    Y. Kitamoto, F. Zhang, M. Abe

    Ferrite: Proceedings of The Eighth International Conference on Ferrites (ICF 8)   1061 - 1063   2001

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  • High Frequency (10 MHz~3GHz) Permeability of (Ni, Zn, Fe)_3_O_4_ Films Prepared by Ferrite Plating at 90℃

    D. Kuruma, M. Yamaguchi, S. Yabukami, Y. Kitamoto, N. Matsushita, K.I. Arai, M. Abe

    Ferrite: Proceedings of The Eighth International Conference on Ferrites (ICF 8)   503 - 505   2001

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  • Temperature (25-80℃) Dependence of Conditions for Synthesizing Magnetite Films by Ferrite Plating

    K. Nishimura, Y. Kohara, N. Matsushita, Y. Kitamoto, M. Abe

    Ferrite: Proceedings of The Eighth International Conference on Ferrites (ICF 8)   654 - 656   2001

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  • Annealing effects of magnetotransport in polycrystalline LSMO thin films

    Hamaya K., Taniyama T., Kitamoto Y., Yamazaki Y.

    Meeting abstracts of the Physical Society of Japan   55 ( 2 )   400 - 400   2000.9

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  • Magnetotransport and Mossbauer study of Fe_3O_4-γfe_2O_3 thin films

    Taniyama T., Kitamoto Y., Yamazaki Y.

    Meeting abstracts of the Physical Society of Japan   55 ( 2 )   400 - 400   2000.9

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  • Improving magnetic and recording characteristics of CoNi ferrite films for perpendicular recording layer

    ZHANG F., MATSUSHITA S., KITAMOTO Y., ABE M.

    24   290 - 290   2000.9

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  • Solution conditions for CoNi ferrite perpendicular magnetic recording thin films

    ZHANG Fuchun, KITAMOTO Yoshitaka, ABE Masanori

    IEICE technical report. Magnetic recording   100 ( 188 )   1 - 4   2000.7

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    CoNi ferrite thin films were prepared for perpendicular magnetic recording media by spin-spray ferrite-plating method. In this paper, solution conditions for CoNi ferrite plating were optimized to increase coercivity H_<c⊥> and remanence ratio (M_r/M_s)_⊥ in perpendicular direction to the film plane. By adjusting the deposition rate, the concentration of NaCo_2 to optimize the ratio of Fe^<2+> to Fe^<3+> in the films and the concentration of CH_3COONH_4 to optimize pH in oxidizing solution, CoNi ferrite films with H_<c⊥> of 3200 Oe and (M_r/M_s)_⊥ of 0.6 were obtained without any heat-treatment. Disk media exhibited reproduced waveforms of di-pluse shape and better frequency responses.

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  • 磁性材料 フェライトめっきによるマグネタイト膜の生成条件

    西村一寛, 小原義久, 北本仁孝, 阿部正紀

    粉体粉末冶金協会講演概要集   2000   118   2000.5

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  • Effect of Ni addition into Co ferrite thin films for perpendicular recording media

    F Zhang, Y Kitamoto, M Abe, M Naoe

    JOURNAL OF APPLIED PHYSICS   87 ( 9 )   6881 - 6883   2000.5

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  • Increase in perpendicular coercivity of Co-Ni ferrite-plated films by Zn ferrite underlayers

    Y Kitamoto, F Zhang, M Abe, M Naoe

    JOURNAL OF APPLIED PHYSICS   87 ( 9 )   6878 - 6880   2000.5

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  • Spin-dependent intergranular transport in magnetite films deposited by ferrite plating

    Y Kitamoto, Y Nakayama, M Abe

    JOURNAL OF APPLIED PHYSICS   87 ( 9 )   7130 - 7132   2000.5

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  • Room temperature synthesis of magnetite films by ferrite plating

    NISHIMURA Kazuhiro, KITAMOTO Yositaka, ABE Masanori

    2000 ( 28 )   45 - 49   2000.2

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  • Development of Perpendicular Magnetic Recording Media Prepared by Co Ferrite-Plating Method

    ZHANG Fuchun, KITAMOTO Yoshitaka, ABE Masanori, KANTAKE Shuusuke

    2000 ( 28 )   51 - 54   2000.2

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  • Faraday rotation in annealed granular Co-SiO_2_ films

    E. Takeda, S. Seino, F. Shirasaki, Y. Kitamoto, M. Abe

    Trans. Mater. Res. Soc. Jpn   25 ( 1 )   11 - 14   2000

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  • Microstructure and magnetic properties of ferrite thin films prepared by sputtering and plating

    Yoshitaka Kitamoto, Shigeki Nakagawa, Masanori Abe, Masahiko Naoe

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   47 ( 2 )   165 - 170   2000

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    DOI: 10.2497/jjspm.47.165

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  • Solution conditions for CoNi ferrite perpendicular magnetic recording thin films

    Fuchun Zhang, Yoshitaka Kitamoto, Masanori Abe

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   47 ( 7 )   730 - 732   2000

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    DOI: 10.2497/jjspm.47.730

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  • Magnetoresistance in Magnetite Films Prepared by Ferrite Plating

    KITAMOTO Y., NAKAYAMA Y., ABE M.

    Journal of the Magnetics Society of Japan   24 ( 4-2 )   619 - 622   2000

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    Fe3-xO4 films prepared by ferrite plating exhibited negative magnetoresistance associated with spin-dependent intergranular transport. The Fe3-xO4 plated films were composed of Fe3O4, γ-Fe2O3, α-FeOOH, and γ-FeOOH. We investigated the relationship between the concentration of NaNO2 in the oxidizing solution and annealing, and the degree of oxidation, magnetic properties, and current-in-plane (CIP) electrical properties. Resistivity was about 0.3-500 μcm, which is higher than that of bulk magnetite (10-2 μcm). MR ratios taken in the maximum field of 2.5 kOe increased as much as 5.7% with increasing concentrations of NaNO2. Mössbauer spectroscopy and electrical evaluation showed that an increase in Fe3+ ion content, in other words, an increase in insulating region, raised the resistivity and the MR ratio with increasing concentrations of NaNO2. The temperature dependence of the resistivity suggested that the magnetoresistance is caused by spin-dependent tunneling through the insulating region that existed in the grain boundaries.

    DOI: 10.3379/jmsjmag.24.619

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  • Ni addition into Co ferrite-plated films

    Fuchun Zhang, Yoshitaka Kitamoto, Masanori Abe

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   47 ( 2 )   171 - 174   2000

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    DOI: 10.2497/jjspm.47.171

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  • Room-temperature Syntheis of Magnetite Films by Ferrite Plating

    NISHIMURA K., KOHARA Y., KITAMOTO Y., ABE M.

    Journal of the Magnetics Society of Japan   24 ( 4-2 )   515 - 517   2000

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    Fe3O4 (magnetite) films were successfully grown at room temperature by ferrite plating from an aqueous solution of FeCl2, utilizing Fe2+ → Fe3+ oxidation realized by adding an aqueous solution of NaNO2 + NH3 to the FeCl2 solution. Since we found that the Fe2+/Fe3O4 (solid) boundary line in the potential-pH diagram of iron shifts to the higher pH region, we increased the pH of the aqueous solution from 5.0-6.8 (at which previous plating was performed at 60°C-100°C) to 7.7-8.8. This facilitated the formation of magnetite films, which consist of single-phase magnetite, as revealed by X-ray diffraction. The magnitude of the films' saturation magnetization is equal to that of bulk samples. The film deposition rate was measured as a function of the pH and the concentration of NaNO2.

    DOI: 10.3379/jmsjmag.24.515

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  • Electrical and Magnetic Properties of Magnetite Films Prepared by Ferrite Plating

    Y. Nakayama, T. Ishikawa, Y. Kitamoto, M. Abe

    Trans. Materials Research Society of Japan   25 ( 4 )   1151 - 1154   2000

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  • Preparation of Hexaferrite Thin Films by Chelation Ferrite Plating with Post Deposition Annealing

    N. Matsushita, M. Ohnishi, S. Miyazaki, Y. Kitamoto, M. Abe

    Ferrites: Proceedings of 8th Inter. Conf. Ferrites(ICF8)   660 - 662   2000

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  • Conditions for Synthesizing Magnetic Films at Room Temperature by Ferrite Plating: Discussion Based on Equilibrium Kinetics

    Kazuhiro Nishimura, Yoshihisa Kohara, Yoshitaka Kitamoto, Masanori Abe

    Trans. Materials Research Society of Japan   25 ( 4 )   1187 - 1190   2000

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  • 反応生成物をバリアとしたLa_1-x_Sr_x_MnO_3_薄膜の低磁場磁気抵抗効果

    浜屋宏平, 谷山智康, 北本仁孝, 山崎陽太郎

    第24日本応用磁気学会学術講演概要集   191   2000

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  • Ferrite Plating of Styrene-Glycidyl Methiacrylate Laetx Particles for Bioseparation and DNA Diagnosis

    M. SAKAI, N. MATSUSHITA, Y, KITAMOTO, H. KAWAGUCHI H, HANDA M. ABE

    Ferrites: Proceedings of 8th Inter. Conf. Ferrites(ICF8)   111 - 113   2000

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  • ダブルぺロブスカイト型酸化物Sr_2_FeMoO_6_の磁気構造

    佐久間洋志, 谷山智康, 北本仁孝, 山崎陽太郎

    第24日本応用磁気学会学術講演概要集   55   2000

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  • Arイオンミリング法によるLSMO薄膜の微細加工、

    直江昌武, 浜屋宏平, 谷山智康, 北本仁孝, 山崎陽太郎

    第24日本応用磁気学会学術講演概要集   88   2000

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  • Bi-TIG Particles Prepared bu Different coprecipitation Procedure

    C.S. Kuroda, T. Taniyama, Y. Kitamoto, Y. Yamazaki

    第24日本応用磁気学会学術講演概要集   237   2000

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  • Microfabrication of LSMO Wires by Dry Eching Process,

    M. Naoe, T. Taniyama, Y Kitamoto, Y. Yamazaki

    Digests of PMRC 2000   115   2000

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  • Spin-Dependent Intergranular Transport in Magnetite Films Deposited by Ferrite Plating

    Y. Kitamoto, Y. Nakayama, M. Abe

    J. Appl. Phys.   87 ( 9 )   7130 - 7132   2000

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  • Depoisition Rate of Magnetite Films Synthesized by Ferrite Plating at Room Temperature

    NISHIMURA Kazuhiro, KOHARA Yoshihisa, KITAMOTO Yoshitaka, ABE Masanori

    J. Jpn. Soc. Powder Powder Metallurgy   47 ( 7 )   733 - 736   2000

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    Magnetite (Fe3O4) films were successfully grown at 24°C from an aqueous solutions of FeC12 into which an oxidizing solution of (1) NaNO2 + NH3 (pH-adjuster) +CH3COONH4 (pH-buffer), (2) NaNO2+NH3+NH4C1(pH-buffer), or (3) NaNO2+NH3, was added. Films of single phase Fe3O4, as revealed by X-ray diffractometry, were obtained at pH=8-9. The pH value is increased from pH=5-7 at which single phase Fe3O4 films were synthesized previously at 60°C, as predicted from theory. The deposition rates of the Fe3O4 films take maximum values of 2.3 nm/min., 11.4 nm/min., and 6.3 nm/min. when oxidizing solution of (1), (2) and (3) were used, respectively. The films grown using the oxidizing solution. (3) were smooth in surface but those grown using (1) and (2) had rough surfaces.

    DOI: 10.2497/jjspm.47.733

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  • Effect of Zn Ferrite Underlayers on Magnetic Properties and Recording Characteristics for Co-Ni Ferrite Media

    F. Zhang, Y. Kitamoto, M. Abe

    Trans. Materials Research Society of Japan   25 ( 4 )   1175 - 1178   2000

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  • Ferrite Thin Film Devices Fabricated by Low Temperature Processing in Aqueous Solution

    Masanori Abe, Kazuhiro Nishimura, Yoshitaka Kitamoto

    The Minerals, Metals & Materials Society   219 - 224   2000

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  • Magnetoresistance in Magnetite Films Prepared from Aqueous Solution at Room Temperature

    K. Nishimura, Y. Kohara, Y. Kitamoto, M.Abe

    J. Appl. Physics   87 ( 9,Pt.3 )   7127 - 7129   2000

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  • Magnetic material. Deposition rate of magnetite film by the room temperature ferrite plating.

    NISHIMURA KAZUHIRO, KOHARA YOSHIHISA, KITAMOTO YOSHITAKA, ABE MASANORI

    粉体粉末冶金協会講演概要集   1999   227   1999.11

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  • Developing Perpendicular Magnetic Recording Media by Ferrite Plating from Aqueous Solution

    ABE M., KITAMOTO Y.

    IEICE technical report. Magnetic recording   99 ( 420 )   57 - 63   1999.11

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    For applying to perpendicular magnetic recording, ferrite films are prepared by ferrite plating from an aqueous solution at 85-90℃; Co-ferrite films for recording media and NiZn ferrite films for high permeability underlayers. The Co-ferrite films have a prominent perpendicular magnetic anisotropy, exhibiting excellent magnetic hysteresis loops with Hc=&sim;3200Oe. This paper describes improvement of magnetic properties of the ferrite films by optimizing plating conditions, and reports preliminary results of signal retrieval performed on the Co-ferrite films.

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  • フェライトめっき法によるマグネタイト膜の室温

    西村一寛, 小原義久, 北本仁孝, 阿部正紀

    日本応用磁気学会学術講演概要集   23   400   1999.10

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  • Magnetic properties and recording performance of CoNi ferrite perpendicular media

    KITAMOTO Y., ZHANG F., ABE M., NAOE M.

    23   36 - 36   1999.10

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  • Magnetoresistance in magnetite films prepared by ferrite plating

    KITAMOTO Y., NAKAYAMA Y., ABE M.

    23   504 - 504   1999.10

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  • Intergranular coupling and activation volume of Co-Ni ferrite thin films with high coercivity above 3 kOe

    Y Kitamoto, F Zhang, S Kantake, F Shirasaki, M Abe, M Naoe

    IEEE TRANSACTIONS ON MAGNETICS   35 ( 5 )   2694 - 2696   1999.9

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  • Nanostructured oxide films by ferrite plating with sonochemistry

    Y Kitamoto, M Abe

    NANOSTRUCTURED MATERIALS   12 ( 1-4 )   41 - 44   1999.7

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  • Co ferrite films with excellent perpendicular magnetic anisotropy and high coercivity deposited at low temperature

    Y Kitamoto, S Kantake, F Shirasaki, M Abe, M Naoe

    JOURNAL OF APPLIED PHYSICS   85 ( 8 )   4708 - 4710   1999.4

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  • Low-temperature fabrication of Co ferrite thin films with high coercivity for perpendicular recording disks by wet process

    Y Kitamoto, S Kantake, F Shirasaki, M Abe, M Naoe

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   193 ( 1-3 )   97 - 100   1999.3

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  • Co-Ferrite Perpendicular Magnetic Recording Media Prepared by Spin-Spray Ferrite-Plating

    F. Zhang, S. Kantake, Y. Kitamoto, M. Abe

    Trans. Mater. Res. Soc. Jpn.   24 ( 4 )   651 - 653   1999

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  • Magnetite film growth at 30℃on organic monomolecular layer, mimicking bacterial magnetosome synthesis

    M. Abe, T. Ishihara, Y. Kitamoto

    J. Appl. Phys.   85 ( 8, Pt.2B )   5705 - 5707   1999

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  • Spin-Spray Ferrite-Plated Co Ferrite Films with High Coercivity for Perpendicular Magnetic Recording Media

    Fuchun Zhang, Shusuke Kantake, Yoshitaka Kitamoto, Masanori Abe

    IEEE Trans. Magn.   35 ( 5,Pt.1 )   2751 - 2753   1999

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  • Nanostructured oxide films by ferrite plating with sonochemistry

    Yoshitaka Kitamoto, Masanori Abe

    Nanostructured Materials   12 ( 1 )   41 - 44   1999

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    DOI: 10.1016/S0965-9773(99)00062-8

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  • Electro-Ferrite Plating of Magnetite at 24-80℃

    Kazuhiro Nishimura, Yoshitaka Kitamoto, Masanori Abe

    IEEE Trans. Magn.   35 ( 5,Pt.1 )   3043 - 3045   1999

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  • Temperature Dependence of Films Deposition Rate in Electro-Ferrite Plating of Magnetite

    K. Nishimura, Y. Kitamoto, M. Abe

    Proc. 2nd Magneto-Electronics Int. Symp.   415   1999

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  • Electro-Ferrite Plating of Fe_3_O_4_ Films from Aqueous Solutions of FeCl_2_ Mixed with Various pH-Adjusting Solutions

    Kazuhiro Nishimura, Yoshitaka Kitamoto, Masanori Abe

    Trans. Mater. Res. Soc. Jpn.   24 ( 4 )   663 - 665   1999

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  • Deposition Rate of Magnetite Films Prepared by Electroless Ferrite Plating

    K. Nishimura, Y. Kitamoto, M. Abe

    Proc. 2nd Magneto-Electronics Int. Symp.   101   1999

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  • MR Effect of Magnetite Films Prepared by Ultrasound-Enhanced Ferrite Plating

    Y. Nakayama, S. Kuwabara, Y. Kitamoto, M. Abe

    Trans. Mater. Res. Soc. Jpn.   24 ( 4 )   643 - 645   1999

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  • Preparation of Ferrite Films for Electrical Insulation by Ultrasound-Enhanced Ferrite Plating

    Y. Nakayama, H. Yajima, Y. Kitamoto, M. Abe

    IEEE Trans. Magn.   35 ( 5,Pt.1 )   3040 - 3042   1999

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  • The Magnetic Recording Characters of Co Ferrite Perpendicular Magnetic Recording Media Prepared By Solution Process

    ZHANG Fuchun, KANTAKE Shuusuke, KITAMOTO Yoshitaka, ABE Masanori

    1998 ( 216 )   17 - 19   1998.12

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  • Effect of solution component in Fe_3O_4 Electroplating

    NISHIMURA Kazuhiro, KITAMOTO Yositaka, ABE Masanori

    1998 ( 216 )   11 - 16   1998.12

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  • Enhanced Phenomenon of Magneto-optical Effect in Photonic Crystal

    TAKEDA Eishi, ABE Masanori, SHIRASAKI Fumio, KITAMOTO Yoshitaka, INOUE Mitsuteru, ARAI Ken Ichi

    1998 ( 201 )   49 - 53   1998.12

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  • Magneto-optical and Optical Characterization of Granular Co-Au and Co-AlO_x Films

    TAKEDA E., TODOROKI N., KITAMOTO Y., ABE M., OHNUMA S., MASUMOTO K., GORODETSKY Gad, INOUE M., ARAI K. I.

    IEICE technical report. Magnetic recording   98 ( 281 )   17 - 22   1998.9

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    We have performed exprimental and theortical researches of optical and magneto-optical properties in granular magnetic structures in which magnetic ultra-fine particles were dispersed in non-magnetic matrices.Granular Ni-PVC films prepares by apin coating method exhibited Faraday effect(Faraday rotation)2〜3 times stronger than that calculated from using effective dielectric permeability as complex medium.In granular Co-SiO_2 and Fe-SiO_2 films perpared by RF sputter deposition, similar enhancement of Faraday effect were observed in the process of increasing magnetic particle in size by annealing. These enhancement of magneto-optical effect in granular C0-Au and Co-AlO_x films prepared by vacuum evaporation and sputtering, respectively, will be discussed relating to improvement of crystal structure and localization of light in disordered media.

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  • 超音波励起・フェライトめっき法--プラスチック超微粒子をフェライトで被覆する

    阿部 正紀, 北本 仁孝

    超音波techno   10 ( 6 )   29 - 32   1998.6

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  • 2)垂直磁気異方性Coフェライト膜の作製(<100℃)(画像情報記録研究会)

    北本 仁孝, 寒竹 秀介, 白崎 文雄, 高谷 慎一, 阿部 正紀

    映像情報メディア学会誌 : 映像情報メディア   52 ( 3 )   294 - 294   1998.3

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  • 垂直磁気ディスク用Co基合金/Ni-Znフェライト二層膜に関する研究 Reviewed

    北本仁孝

    1998.1

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  • Preparation of Co Ferrite Thin Films for Magnetic Recording Media by the Ferrite-Plating Method

    YOSHITAKA KITAMOTO

    Journal of The Magnetics Society of Japan   22 ( 4-2 )   477 - 479   1998

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    Language:Japanese   Publisher:The Magnetics Society of Japan  

    Perpendicular anisotropic CoxFe3-xO4 films 25-200 nm in thickness for perpendicular magnetic recording media were successfully obtained by the spin-spray ferrite-plating method at 90°C. The perpendicular coercivity Hc⊥of the films took a maximum at around 0.5, and the value of Hc⊥ was over 2000 Oe even for a film thickness of 25 nm. By optimizing the concentration of NaNO2 in the oxidizing solution, the in-plane coercivity Hc// was reduced to 300 Oe, while Hc⊥ was kept at over 2000 Oe. Mössbauer analyses show that the films have excellent perpendicular magnetic anisotropy. The angular dependence of the coercivity shows that a reversal of the magnetization takes place in the rotation mode as in Co-Cr sputter-deposited films.

    DOI: 10.3379/jmsjmag.22.477

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    Other Link: http://dl.ndl.go.jp/info:ndljp/pid/10463880

  • Ferrite-Plated Films and Their Applications

    ABE Masanori, KITAMOTO Yoshitaka

    Jitsumu Hyomen Gijutsu   49 ( 7 )   728 - 733   1998

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    Language:Japanese   Publisher:The Surface Finishing Society of Japan  

    DOI: 10.4139/sfj.49.728

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    Other Link: https://jlc.jst.go.jp/DN/JALC/00055213943?from=CiNii

  • Preparation of Co Ferrite Thin Films for Magnetic Recording Media by the Ferrite-Plating Method

    KITAMOTO Y., KANTAKE S., TAKAYA S., SHIRASAKI F., ABE M., NAOE M.

    Journal of the Magnetics Society of Japan   22 ( 4-2 )   477 - 479   1998

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    Language:Japanese   Publisher:The Magnetics Society of Japan  

    Perpendicular anisotropic CoxFe3-xO4 films 25-200 nm in thickness for perpendicular magnetic recording media were successfully obtained by the spin-spray ferrite-plating method at 90°C. The perpendicular coercivity Hc⊥of the films took a maximum at around 0.5, and the value of Hc⊥ was over 2000 Oe even for a film thickness of 25 nm. By optimizing the concentration of NaNO2 in the oxidizing solution, the in-plane coercivity Hc// was reduced to 300 Oe, while Hc⊥ was kept at over 2000 Oe. Mössbauer analyses show that the films have excellent perpendicular magnetic anisotropy. The angular dependence of the coercivity shows that a reversal of the magnetization takes place in the rotation mode as in Co-Cr sputter-deposited films.

    DOI: 10.3379/jmsjmag.22.477

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    Other Link: http://dl.ndl.go.jp/info:ndljp/pid/10463880

  • Preparation of Co ferrite thin films for magnetic recording media by "Ferrite-plating" method

    KITAMOTO Y., KANTAKE S., TAKAYA S., SHIRASAKI F., ABE M., NAOE M.

    21   452 - 452   1997.10

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  • Enhancement of magneto-optical properties for Co/SiO_ and Fe/SiO_2 granular films

    SEINO S., SATO I., MATSUMIYA H., SHIRASAKI F., KITAMOTO Y., ABE M.

    21   403 - 403   1997.10

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  • NiZn Ferrite Film Preparation by Ultrasound-Enhanced Ferrite Plating

    YAJIMA H., NAKAYAMA Y., KITAMOTO Y., ABE M.

    21   448 - 448   1997.10

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  • Measurement and analysis of magneto-optical properties for granular magnetic thin films

    SEINO S., KITAMOTO Y., ABE M.

    IEICE technical report. Magnetic recording   97 ( 245 )   37 - 43   1997.9

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    We studied the optical and magneto-optical properties of granular films in which magnetic fine particles are dispersed in the binders. The Ni/PVC granular films, prepared by spin coating with Ni fine particles dispersed in PVC matrix, exhibited faraday effect 2〜3 times stronger than that calculated using effective dielectric permeability tensor for the films. This was not satisfactorily explained even by considering the effect of congelation of the Ni powders in the matrix, indicating that magneto-optical effect is enhanced in the granular structure. Faraday effect in sputter-deposited Co/SiO_2 and Fe/SiO_2 granular films increased as the Co and Fe particles increased in size by annealing, which, however, decreased as the particles size further increased by annealing.

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  • Ferromagnetic Film Preparation by Ultrasound-Enhanced Ferrite Plating

    YAJIMA Hiroshi, NAKAYAMA Yoshiyasu, KITAMOTO Yoshitaka, ABE Masanori

    IEICE technical report. Magnetic recording   97 ( 245 )   21 - 27   1997.9

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    Ferrite plating enables crystalline spinel ferrite films to be grown form an aqueous solution at low temperature (< 100℃). This facilitates the fabrication of new ferrite film devices using non-heat-resistant materials as substrates. Combining the ferrite plating with sonochemistry, application of power ultrasound waves to stimulate chemical reactions, we successfully improved the crystallising, and therefore the quality of the films. Modifying the reaction cell and plating conditions further improved the film quality.

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  • Sputter-deposition of Co-Cr-Ta alloy layers on Ni-Zn ferrite plated underlayers

    Y Kitamoto, MH Kim, S Kantake, M Abe, M Naoe

    IEEE TRANSACTIONS ON MAGNETICS   33 ( 5 )   3085 - 3087   1997.9

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  • Ferrite Plated Films for Magnetic Recording Applications

    KITAMOTO Yoshitaka, KIM Myung-ho, KANTAKE Shusuke, ABE Masanori

    IEICE technical report. Magnetic recording   96 ( 486 )   37 - 43   1997.1

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    Ferrite plating enables crystalline spinel ferrite films to be grown from an aqueous solution at low temperature (<100℃). We investigated internal stress and microstructure in the plated films to apply to backlayers for doublelayered perpendicular recording media. It is important to control surface morphology of the ferrite plated layers in order to deposit Co-Cr alloy layers with fine microstructure. To satisfy this requirement, it is necessary to accelerate migration of metal ions on growing films. Thus we tried power ultrasound enhancement for the ferrite plating.

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  • Preparation of Oxide Thin Films by Ferrite Plating and their Applications

    ABE Masanori, KITAMOTO Yoshitaka

    IEICE technical report. Magnetic recording   96 ( 246 )   1 - 8   1996.9

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    Ferrite plating enables crystalline spinel ferrite films to be grown from an aqueous solution at low temperature (<100℃). This technique facilitates the fabrication of new ferrite film devices on non-heat-resistant materials. This paper reports principles and features (in particular, low temperature process) of the ferrite plating, and applications such as magnetic recording media, microwave devices, and bio-medical applications. It also describes that power ultrasound irradiation during the ferrite plating improves the magnetic and structural properties of the plated films.

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  • A Novel Technique : Ultrasound enhanced Ferrite Plating, Applied to Ferrite-Capsulation of Polymer Microspheres

    ZHANG M., KITAMOTO Y., HAIJIMA S., MATSUMOTO K., ABE M.

    20   158 - 158   1996.9

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  • Deposition of Co-Cr films with excellent C-axis orientation and uniform thickness for rigid disks using compact sputtering apparatus

    Y Kitamoto, M Abe, M Naoe

    IEEE TRANSACTIONS ON MAGNETICS   32 ( 5 )   4547 - 4549   1996.9

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  • Preparation of Co-Cr alloy/Ni-Zn ferrite doublelayered films for perpendicular magnetic tape

    Y Kitamoto, M Abe, M Naoe

    IEEE TRANSACTIONS ON MAGNETICS   32 ( 5 )   3834 - 3836   1996.9

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  • EFFECT OF SUBSTRATE-TEMPERATURE ON MAGNETIC AND MICROSTRUCTURAL PROPERTIES OF SPUTTERED CO-CR FILMS WITH PERPENDICULAR MAGNETIC-ANISOTROPY

    Y UCHIYAMA, H SATO, Y KITAMOTO

    IEEE TRANSACTIONS ON MAGNETICS   28 ( 5 )   2010 - 2017   1992.9

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  • PERPENDICULAR COERCIVITY OF CO-CR FILMS

    Y UCHIYAMA, H SATO, Y KITAMOTO, UM HWANG

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   30 ( 10 )   2485 - 2488   1991.10

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    Web of Science

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  • Influence of Co-Zr-Nb Intermediate Layer on Properties of Double Layered Perperdicular Media

    Y. Uchiyama, H. Sato, Y. Kitamoto, K. Ishibashi, U. Hwang

    Journal of Magnetics Society Japan, Supplement   15 ( 52 )   995   1991

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  • Influence of Co-Zr-Nb Intermediate Layer on Properties of Double Layered Perperdicular Media

    Y. Uchiyama, H. Sato, Y. Kitamoto, K. Ishibashi, U. Hwang

    Journal of Magnetics Society Japan, Supplement   15 ( 52 )   995   1991

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  • CONTROL OF INTERNAL-STRESS OF CO-CR FILMS DEPOSITED BY FACING TARGETS SPUTTERING

    S NAKAGAWA, Y KITAMOTO, M NAOE

    IEEE TRANSACTIONS ON MAGNETICS   26 ( 1 )   106 - 108   1990.1

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  • Control of Internal Stress of Co-Cr Film Deposited by Facing Targets Sputtering

    Shigeki NAKAGAWA Yoshitaka, KITAMOTO, Masahiko NAOE

    IEEE Transactions on Magnetics   26 ( 1 )   106   1990

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  • Maltilayered Co-Cr Films with Non-Magnetic Intermediate Layers by FTS Systen.(共著)

    Y. Niimura, Y. Kitamoto, S. Nakagawa, M. Naoe

    IEEE Transactions on Magnetics   22 ( 5 )   2464   1987

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  • Maltilayered Co-Cr Films with Non-Magnetic Intermediate Layers by FTS Systen.(共著)

    Y. Niimura, Y. Kitamoto, S. Nakagawa, M. Naoe

    IEEE Transactions on Magnetics   22 ( 5 )   2464   1987

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Presentations

  • Fabrication of Langmuir-Blodgett film composed of Zinc Oxide nanoparticles

    2010 

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  • 磁気光学顕微鏡による(Ga,Mn)Asの磁化反転過程の局所観察

    第55回応用物理学関係連合講演会  2008 

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  • Langmuir-Blodgett法を用いた酸化亜鉛ナノ粒子薄膜の作製と評価

    2010 

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  • Influence of Chemical Conditions in Fabrication of Bi-YIG Precursor on Morphological and Magnto-Optical Response of Its Particulate Film

    2005 

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  • CoZrNb/Fe-C Discontinuous Multilayer Films for GHz Applications

    2005 

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  • High magnetocrystalline anisotoropy and thermal stability in isolated iron-platinum nanoparticle-monolayer with protective coating

    2005 

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  • CoZrNb/Fe-C Discontinuous Multilayer Films for GHz Applications

    2005 

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  • Synthesis of Fe-Pd nanoparticles by polyol reduction process and their magnetic properties

    2005 

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  • L10相Fe-Ni-Ptの製膜と磁気特性

    第29回日本応用磁気学会学術講演会  2005 

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  • Influence of Chemical Conditions in Fabrication of Bi-YIG Precursor on Morphological and Magnto-Optical Response of Its Particulate Film

    2005 

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  • Synthesis of Fe-Pd nanoparticles by polyol reduction process and their magnetic properties

    2005 

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  • High magnetocrystalline anisotoropy and thermal stability in isolated iron-platinum nanoparticle-monolayer with protective coating

    2005 

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  • Two magnetic phases in (Ga,Mn)As

    K. Hamaya, T. Taniyama, Y. Kitamoto, Y. Yamazaki

    The 49th Annual Conference on Magnetism & Magnetic Materials  2004 

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Awards

  • 粉体粉粉末冶金協会研究功績賞

    2021.6   粉体粉末冶金協会   磁性ナノ粒子及び集積体によるバイオメディカル応用のための材料・デバイス開発に関する研究

    北本 仁孝

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  • 粉体粉末冶金協会2010年度論文賞

    2011.5   粉体粉末冶金協会   FePt/SiO2複合型磁性ナノ粒子の作製

    渕上輝顕, 河村亮, 山崎陽太郎, 北本仁孝, 中川勝, 並木禎尚

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  • 日本応用磁気学会論文賞

    2000  

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  • コニカ画像科学奨励賞

    1999  

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  • Young Researcher Award (IUMRS-ICA-97)

    1997  

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Research Projects

  • 磁性ナノ粒子-生体分子間相互作用による磁気緩和の変調と高感度バイオセンシング

    Grant number:21H01760  2021.4 - 2024.3

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    北本 仁孝

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    Grant amount:\17160000 ( Direct Cost: \13200000 、 Indirect Cost:\3960000 )

    生体分子である核酸、タンパク質、糖鎖、脂質と相互作用する仕組みを付加した酸化鉄ナノ粒子を作製し、各種生体分子と相互作用する様子を、形態的、光学的、磁気的に評価した。また、交流磁化計測装置開発においてはより高感度な計測回路の設計指針を示すことができた。加えて、計測した交流磁化の周波数特性の結果を解析する手法としてデータ科学に基づいた方法を開始し、その有効性を示すことがでた。
    DNA検出用磁性ナノ粒子プローブ開発においては、10塩基の単鎖DNAをプローブとして磁性ナノ粒子に固定化するプロセスを確立し、より分散性を向上させる溶液条件を明らかにした。創製した磁性ナノ粒子プローブを用いて22塩基のマイクロRNAを模したDNAと相互作用が起こることを交流磁化計測から明らかにした。その検出レベルは感染症などの検査のためのPCRにおいて検出する核酸のレベルと同等、あるいはより高感度になる可能性があることがわかった。
    交流磁化計測装置開発においては、生体分子と磁性ナノ粒子プローブとの間の複雑かつ不均一な生化学反応を交流磁化状態の分布計測を実現するための計測回路について検討した。詳細な分布計測のためには交流磁化の周波数特性において数1000点レベルの大量のデータが必要となるが、周波数をスキャンしながら高速で計測するための回路においてコンデンサなどの電子部品で回路のインピーダンスを調節することが有効であることを明らかにした。
    交流磁化の周波数特性において磁性ナノ粒子の磁化状態分布を解析するために、フィッティングや主成分分析を導入し、昨年度まで行っていたゲル中の磁性ナノ粒子の振舞を解析することにおいて、その有効性を示した。またより複雑な磁性ナノ粒子と高分子との相互作用について、その解析に適用できる可能性があることも示した。

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  • Biosensing by dynamic magnetization measurement of stimuli-responsive magnetic hydrogels

    Grant number:18H01824  2018.4 - 2021.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    Kitamoto Yoshitaka

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    Grant amount:\17290000 ( Direct Cost: \13300000 、 Indirect Cost:\3990000 )

    Ferrogels composed of magnetic nanoparticles and stimuli-responsive hydrogels have been synthesized as a magnetic label for chemical/biochemical biosensors. Magnetic nanoparticles are dispersed in a stimuli-responsive polymer hydrogel with keeping a capability of physical motions such as rotation and vibration, exhibiting a magnetic relaxation (Brownian relaxation) based on their hydrodynamic behaviors against alternating magnetic fields. Modulations of the hydrodynamic behaviors of magnetic nanoparticles in the ferrogels have been detected by dynamic magnetization measurements of the ferrogels with a swelling behavior of a pH-responsive polymer hydrogel. The detection of ammonia gas has been successfully demonstrated using the pH-responsive ferrogel from the dynamic magnetization measurements.

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  • Ultrafast manipulation of magnetization with optical or lattice-wave excitations and its applications

    Grant number:22226002  2010.4 - 2016.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (S)

    Munekata Hiro, KITAMOTO Yoshitaka, NISHIBAYASHI Kazuhiro

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    Grant amount:\213460000 ( Direct Cost: \164200000 、 Indirect Cost:\49260000 )

    Manipulation of magnetization with femotosecond laser pulses has been studied in order to find ways to break the two-picosecond (ps) limit shown by magnetic pulses. The photo-excited precession of magnetization (PEPM) in ferromagnetic semiconductors is found to be attributed to the change in magnetic anisotropy due to photo-ionization of Mn ions, with which non-linear control of the precession amplitude has also been demonstrated by a pair of sub-ps-separated laser pulses. Furthermore, PEPM with MW/cm2 pulse power has been found possible in the Co-Pd multilayers, which indicates the discovery of candidate materials for spin-photonic devices. The spatial de-multiplexing of polarization modulated signals has been demonstrated using the optical fibers attached with magnetic thin films, through which fundamentals of spin-photonic devices are experimented. Helicity switching of circular polarized light at 100 kHz has been demonstrated at room temperature by dual-injection spin-LED.

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  • 磁性ナノ粒子プローブを用いた新型インフルエンザの超高感度迅速診断チップ

    Grant number:22300180  2010 - 2012

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    並木 禎尚, 北本 仁孝

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    Grant amount:\13520000 ( Direct Cost: \10400000 、 Indirect Cost:\3120000 )

    従来の簡易診断法の最小検出限界を低減できる超高感度・迅速な磁気バイオセンサチップを開発した。その実現のための要素技術は次の3点に集約され、これらの達成が本申請研究の目的である。
    1) 一次抗体被覆ナノ粒子・抗原複合体の磁気濃縮(微小空間での磁気分離による、希薄検体からの抗原抗体複合体の高効率捕捉)と、二次抗体によるシグナル増幅。
    2) マイクロ流路内のブラウン運動活性化と層流による抗原抗体反応の活性化。
    3) 高い交流磁界応答を示す磁性粒子プローブ、高感度センシング、磁性粒子-免疫複合体の物理的捕捉、トンネル磁気抵抗効果型磁気センサーと駆動回路技術から構成)。
    ・本成果により、新型インフルエンザの超早期診断率の大幅な向上が見込まれる。迅速・適切な対応が可能になるため、重症化・蔓延の防止に大きく貢献する。急増している新型インフルエンザは、従来型よりも致死率が高く、本申請は緊急性の高いテーマである。
    ・日本が世界をリードするナノテクノロジーを応用するため、日本の強みを活かせる。
    ・手のひらにのるサイズのハードディスクドライブのように小型化が可能で簡便なツールとなりうる。量産技術がある程度確立しているので、使い捨てと考えても余りコストがかからない。
    ・他疾患の診断にも応用できるため、大きな波及効果が期待できる。
    本年度は、抗原抗体反応を迅速・鋭敏に検出できる磁気バイオセンサチップを完成させ、特許出願、論文投稿、学会発表を行っている。

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  • Developing technology for imaging cancer tumors and sentinel lymph nodes utilizing sonic wave emission by magnetically stimulated particles

    Grant number:21240054  2009 - 2011

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    MATSUSHITA Nobuhiro, HANDA Hiroshi, KITAMOTO Yoshitaka, OGAWA Makoto, MINAMIYA Yoshihiro

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    Grant amount:\46670000 ( Direct Cost: \35900000 、 Indirect Cost:\10770000 )

    In order to apply to sentinel lymph node mapping by emission of acoustic waves by magnetically-stimulated particles, we developed new devices which will enable 3D magnetic particle imaging by using only one microphone. They are(1) Bunny ear Reflector Microphone(BERM) in which a microphone is mounted on a asymmetric position of a reflector and the impulse response of burst acoustic waves propagated directly and reflected by the reflector is analyzed. And(2)"Random Path Holophonic Sensor" in which the impulse response of burst ultrasonic waves propagated through the small apertures distributed randomly(after maximal-length sequences) on a microphone head is analyzed. Simulation experiments confirmed the operation principle of our new devices. We also developed "two-step ligand exchange reaction", by which we successfully synthesized ferrite beads with narrow size distribution ; when their average size was 20 nm they showed strong magneto-acoustic effect and they were accumulated at the first lymph nodes(pseudo sentinel lymph nodes) of a mouse at a high efficiency.

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  • Nano-magnetic sensing system for biomedical devices

    Grant number:20310077  2008 - 2010

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    KITAMOTO Yoshitaka, TSUGE Takeharu

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    Grant amount:\19240000 ( Direct Cost: \14800000 、 Indirect Cost:\4440000 )

    We studied developments of magnetic beads and magnetic sensors and their integration in a microfluidic device for detecting protein, DNA, virus, and etc in bio-medical applications. Magnetic beads, which is an assembly composed of Fe-Pt nanoparticles, were obtained using polymer dispersing agents, and they exhibited a high magnetic response. A fabrication process for magnetic-field sensors based on the tunneling-magnetoresistance effect and the integration into a microfluidic device were developed.

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  • Fabrication of innovative functional assemblies using programmed self-organizational processes

    Grant number:20200004  2008 - 2010

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Innovative Areas (Research a proposed research project)

    ISHIKAWA Masamichi, MURATA Satoshi, KAJIKAWA Kotaro, KITAMOTO Yoshitaka

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    Grant amount:\31330000 ( Direct Cost: \24100000 、 Indirect Cost:\7230000 )

    Fabrication processes of formulating large-areal and defect-free assemblies for new functional materials were constructed based on programmed DNA self-organization and colloidal crystal theory. It was clearly presented that charged particles, e.g. colloidal particles and DNA assemblies, were self-organized into the crystalline structures of high perfection and large-area on charged substrates, such as glass and mica. The newly found mechanism was applied to fabricate thin-film photonic materials and meta-materials with noble optical properties.

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  • Elucidation and control of photo-magnetism in ferromagnetic semiconductors

    Grant number:19048020  2007 - 2010

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Priority Areas

    MUNEKATA Hiro, KITAMOTO Yoshitaka

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    Grant amount:\43000000 ( Direct Cost: \43000000 )

    We report experimental accomplishments obtained through the study of light-induced precession of magnetization in ferromagnetic (Ga, Mn) As. In particular, non-thermal influence of optical excitation, coherent control of magnetization with two optical pulses, control of precession frequency, and optical generation of spin-current are described. Progress in the preparation and characterization of lateral-type spin LED is also described.

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  • Concentrated solar heat conversion to solar hydrogen using speciallycation-excess ferrite

    Grant number:19206106  2007 - 2008

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    TAMAURA Yutaka, ABE Masanori, KITAMOTO Masataka, KANEKO Hiroshi, HASEGAWA Noriko

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    Grant amount:\50050000 ( Direct Cost: \38500000 、 Indirect Cost:\11550000 )

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  • 磁性ナノファイバーの創製とマニピュレーション

    Grant number:16656094  2004 - 2005

    日本学術振興会  科学研究費助成事業  萌芽研究

    北本 仁孝

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    Grant amount:\2900000 ( Direct Cost: \2900000 )

    Coアセチルアセトナートを用いたポリオール還元法において,界面活性剤(オレイン酸)と高分子保護剤(trioctylphosphine oxide, TOPO)の両方を添加することによって,2-5nmの径でアスペクト比が10以上のファイバー状のナノ粒子が得られることをもとに検討を進めた.ファイバー状粒子の生成に対する要因のうち,オレイン酸とTOPOの共存,かつオレイン酸とTOPOの投入手順が大きく影響を及ぼすことがわかった.TOPOとCo錯体の比率を変えることによって球状Co粒子との生成割合が変化したが,ファイバー状粒子単独の磁性を評価するのに十分な精製が行なえるレベルには至らなかった.球状粒子では酸化が確認されなかったのに対し,ファイバー状粒子では酸化していることが確認されたが,酸化が粒子の生成中に起こったのか,生成後(精製中あるいは保存中)に起こったのかを断定することはできなかった.
    一方,高い磁気異方性を有する物質を用いてファイバー状のナノ粒子を形成することは磁気記録用に有効であると考えられる.そこで,L1_0規則合金であるFe-Pdナノ粒子の合成においてTOPOを保護剤として用いたが,生成するのは球状粒子のみであった.ファイバー状粒子の生成には析出した金属原子が鎖状のTOPOに配位することが必要であるが,元素による配位能の違いがファイバー状粒子が生成するかどうかに大きな影響を与えるものと推測できる結果であった.
    以上の結果から,本研究では試行することができなかったが,Coをベースとして耐酸化性にすぐれるPtなど貴金属との合金がファイバー状磁性微粒子の生成には適しているのではないかと推測される.

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  • Fabrication of magnetic nanoparticle-array recording media and their evaluation with probe heads

    Grant number:14350180  2002 - 2004

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    KITAMOTO Yoshitaka, TANIYAMA Tomoyasu, MATSUSHITA Nobuhiro

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    Grant amount:\17000000 ( Direct Cost: \17000000 )

    The purpose of the present study is to establish fabrication techniques of Fe-Pt nanoparticle-array magnetic recording media and to evaluate their potential to achieve areal recording density over 1 tera-bit per square inch. The results are shown in the followings.
    1) We studied the relationship between chemical ordering and magnetic anisotropy for powder samples of Fe-Pt nanoparticles, and found that a volume ratio Q of ordered alloy phase evaluated with Mossbauer spectroscopy was a useful parameter to evaluate the chemical ordering. Whereas Q is a parameter for short-range ordering, S obtained from X-ray diffractometry is a parameter for long-range ordering. Magnetic anisotropy was evaluated with the maximum magnetic field of 90 kOe. Distribution of magnetic anisotropy-field H_k for partially ordered Fe-Pt nanoparticles was much broader than that for almost fully ordered Fe-Pt nanoparticles, and the low H_k components were included with a high volume ratio.
    2) Partially ordered Fe-Pt nanoparticles were successfully obtained with polyol reduction method of Fe and Pt salts by using microwave irradiation without any post-synthesis heat-treatment. The Fe-Pt nanoparticles synthesized at 250℃ with microwave irradiation exhibited volume ratio for ordered alloy phase of 60% and magnetic anisotropy field over 80 kOe.
    3) Mixing saturated fatty acid (C_nH_<2n> O_2) molecules to an Fe-Pt nanoparticle suspension assisted the formation of a nanoparticle monolayer on pure water surface without coagulation. Because the surface of the Fe-Pt nanoparticles is hydrophobic, interface energy with water surface is high. The fatty acid molecules probably reduced the interface energy as a buffer layer between the Fe-Pt nanoparticle-monolayer and water surface. Fatty acid molecules with n 【greater than or equal】 14 were effective for the formation, and the best one in view of the formation of regular nanoparticle-array was the molecule with n = 14.
    4) Carbon overcoats deposited with sputtering on Fe-Pt nanoparticle assembly-films successfully prevented the assembly-films from inter-particle sintering. Fe-Pt nanoparticles of 4-5 nm in diameter were kept isolated physically and were chemically ordered after an optimum heat-treatment. However, higher temperature and longer time for the heat treatment were required to achieve proper chemical ordering to fit a specification of high-density recording media for future recording system. Fe-Pt nanoparticle assembly-films with a carbon overcoat annealed under the optimum conditions exhibited that the particle size was 4-5 nm and magnetic anisotropy constant was 4.8x10^7 erg/cm^3.

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  • On-line System Designing for Multi Function DMFCs

    Grant number:13134202  2001 - 2005

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Priority Areas

    YAMAZAKI Yohtaro, KITAMOTO Fusao, KITAMOTO Yoshitaka, WAKI Keiko, TANIYAMA Tomoyasu, HAYASE Masanori

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    Grant amount:\125200000 ( Direct Cost: \125200000 )

    The Research Project D in the Priority Area conducted several studies related to the system development of direct type fuel cells. This group also developed various measurement systems and special analytical methods, to support the other Research Projects, i.e., Research Project A relating to the development of membrane materials, Research Project B relating to the studies of catalyst and electrode materials, and Research Project C relating to the study on the optimization of membrane and electrode assembly (MEA).
    The system development studies in the Project D include 3 tasks, i.e., (1) development of an ethanol fuel cell system as an alternative to the toxic DMFC fuel system, (2) development of PEFCs using alkaline polymer membrane materials, and (3) miniaturization of DMFCs using micro fabrication method.
    (1) A direct ethanol fuel cell is studied and the behavior of the acetaldehyde which is an intermediate product in the anode reaction was investigated. The knowledge obtained in this analysis contributes to the realization of direct ethanol fuel cells (DEFCs).
    (2) Alkaline fuel cells have the advantages that they lower the cathode overpotential, and they provide conditions suitable for catalysts without precious metals. We developed a fuel cell with alkaline membrane. The cell was tested for methanol, ethanol, 2-propanol fuels. The performance of the cell depended on the pH of the fuels. The improvement of the dispersion characteristic of carbon particles was the issue of the alkaline membrane fuel cells.
    (3) Novel micro DMFCs based on MEMS technology were designed and fabricated. The selective plasma etching method was employed to fabricate the gas channels in the cell. This technology reduces the number of the components in a DMFC and reduces the assembly cost as well as reduces their sizes.
    The TEM and SEM observation method for the cross section of MEA using a focused ion beam system, which was developed in this group, clarified the structure of the interface between the electrode and electrolyte membrane in the MEAs, and effectively supported the whole research project in the Priority Area.

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  • 金属磁性酸化物のナノ微細加工とスピン注入への応用

    Grant number:13875115  2001 - 2002

    日本学術振興会  科学研究費助成事業  萌芽研究

    山崎 陽太郎, 山内 尚雄, 谷山 智康, 北本 仁孝, 吉本 護

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    Grant amount:\2100000 ( Direct Cost: \2100000 )

    前年度,磁性酸化物であるマグネタイト薄膜の反応性イオンエッチングを確立したが,それと同様の反応を用いて,ペロブスカイト型マンガン酸化物を微細加工し,スピン注入デバイスの作製を行なった.まず,50ないし100nm厚のLa_<0.7>Sr_<0.3>MnO_3(LSMO)薄膜をSrTiO_3(001)基板上に,RFスパッタ法によりエピタキシャル成長させた.ポジ型レジストを塗布し,電子線リソグラフィにより1μm幅のリフトオフパターンを作製し,50nm厚のTi薄膜をマスクとして電子線蒸着により形成した.反応性イオンエッチングは,RFスパッタ装置を使用し,LSMO薄膜にはCO, NH_3混合ガスによって行なった.投入電力を75W,ガス圧力を0.02Torrと固定して,ガスの混合比を最適化し,CO : NH_3=1:4のときに3.8nm/minのエッチングレートを得た.TiマスクはCF_4ガスを用いた反応性イオンエッチングによって除去した.1μm幅のLSMO細線と直交するように0.5μm幅のCuFe近藤合金の細線をリフトオフにより形成した.スピン注入実験においては,金属系のスピン注入デバイスと同等の10^6A/cm^2程度の通電を行なったが,その際にCuFe部分で細線の断裂が起き,スピン注入によるCuFeの挙動の変化を捉えることはできなかった.その原因として,接合部分におけるジュール熱の発生があげられる.このことはLSMO表面が微細加工のダメージによりオーミック接合を得るのに適していなかったことを示唆していると考えられる.

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  • Development of Magnetooptical Plastic Fiber

    Grant number:12450265  2000 - 2002

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    YAMAZAKI Yohtaro, HIRANO Teruyoshi, TANIYAMA Tomoyasu, KITAMOTO Yoshitaka

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    Grant amount:\16700000 ( Direct Cost: \16700000 )

    This report describes a current sensor using Bi-YIG nanoparticle-dispersed optical prastic fiber with magnetooptical activity. Bi-YIG nanoparticles were prepared by coprecipitation followed by heat treatment. MMA was used for the matrix and PMMA was used for a dispersion agent in the matrix. Both optical absorption coefficient and magnetooptical properties such as saturation Faraday rotation and Veldet constant increased with increasing the volume fraction of the Bi-YIG particle in the fiber. Under the optimized conditions of the fiber length and the volume fraction the Veldet constant, which is the most important parameter for the current sensor, was 10 times as high as rare-earth doped glass. The most preferable wavelength of the optical source was 520 nm.
    Dispersability of the Bi-YIG particles improves the magnetooptical properties. Two additives for the coprecipitation were tried to improve the dispersibility, in other words, to improve grindability during the milling process. One was NaOH solution, and the other was ammonium sulfate. Adding NaOH solution decreased the crystallization temperature, leading to smaller particles after the milling process. TEM observation revealed that the Bi-YIG particles with the size of 20-40 nm were well dispersed in the case of the coprecipitation using NaOH and ammonium sulfate while coagulations exist in the case of the conventional process. The difference in the dispersibility led to the reduction in the absorption coefficient and the increase in the Faraday rotation. The maximum value of figure of merit reached 4.8, which is twice or higher than the conventional one.

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  • Micro-patterned high-density magnetic recording media by self-assembly in solution

    Grant number:11650343  1999 - 2000

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    KITAMOTO Yoshitaka, ABE Masanori, TANIYAMA Tomoyasu, YAMAZAKI Yohtaro

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    Grant amount:\3700000 ( Direct Cost: \3700000 )

    This report describes the preparation of a nanoparticles array for high-density magnetic recording media by a self-assembly process in a solution. Reverse micelle technique for preparing magnetic nanoparticles and self-assembly for arraying the particles were combined.
    It was found that pH values for preparing ferrite particles moved to higher range at low temperature below 60℃, which is the maximum temperature to employ the reverse micelle technique. An ammonia solution was superior to a NaOH solution regarding crystallinity and particle size for synthesizing magnetite or Co ferrite particles. While reaction temperature did not influence the particle size and crystallinity in the range from 25 to 55℃, saturation magnetization increased with increasing the temperature. However, all kinds of the particles obtained in this study exhibited super-paramagnetic properties at room temperature. Adding Co ions to the particles increased coercivity at 5 K, and the maximum value was higher than 10 kOe. However, the Co ferrite particles were still super-paramagnetic. Average particle size was about 10 nm. Transmission electron microscope (TEM) observation and electron diffraction pattern with nano-sized beam showed that a single particle was single crystal.
    TEM observation showed that some particles with the average size of 10 nm assembled and the others with the smaller size distributed without assembling. This result suggests that particles with a uniform size tend to assemble each other. In other words, the particles probably sort themselves with the similar size by self-assembling process.
    This tendency has an effect on manufacturing the array with uniform particles. Micropatternig of particulate films with the width of 2 mm and the pitch of 4 mm were tried with the help of self-assembling organic molecules in order to fabricate patterned magnetic recording media. However, the quality of the pattering was not as good as that of films of only the organic molecules.

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  • Preparation of oxide thim films by ultra-clean ferrite plating and their magnetic properties

    Grant number:09650346  1997 - 1998

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    KITAMOTO Yoshitaka, ABE Masanori

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    Grant amount:\3300000 ( Direct Cost: \3300000 )

    This report describes the ferrite plating using purified clean aqueous solutions to compress the formation of impurity particles, which are incorporated in plated films and degrade their microstructure and magnetic properties. To realize the ultra-clean solutions, 1) a reaction solution and an oxidizing one were prepared using ultrapure water and supplied through membrane filters of 0.1 mum in pore diameter, 2) an ammonia solution was supplied to keep a pH value during the reaction instead of CH_3COONH_4 that forms impurity particles by mixing with Fe^<2+> ions. Magnetite (Fe_3O_4) and Ni-Zn ferrite films were synthesized on glass substrates or polymer spheres.
    The polymer microspheres with ferrite coatings are used as carrier particles for enzyme immunoassay. The ferrite coatings are necessary for collecting the particles using magnetic field. Thickness of the ferrite coatings is required to be equal or less than 50 nm to obtain a good dispersion performance in water. In methods without using the clean solution technique, continuous films with such thickness were not obtained due to large grains of around 100 nm, which were caused by incorporated impurity particles formed in the solution. In the new method, small grains of 10-20 nm were observed in the initial stage. When the layer thickness was 50 nm, the polymer particles were fully encapsulated with ferrite coatings, which have smooth surface and were composed of uniform and small grains. Mossbauer spectra showed that the coatings are composed of magnetite. The saturation magnetization was almost the same as the bulk value. The particles coated with 50 nm-thick magnetite exhibited the excellent dispersion performance in water and efficiency of magnetic separation by the magnetic field of 40 Oe. These performances were superior to those of the product in the market for enzyme immunoassay.

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  • Preparation of magnetic films by new technique "ultrasound enhanced" ferrite plating

    Grant number:08455137  1996 - 1997

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    ABE Masanori, SHIRASAKI Fumio, KITAMOTO Yoshitaka

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    Grant amount:\7800000 ( Direct Cost: \7800000 )

    Ferrite plating invented by the investigators enables formation of ferrite films from aqueous solution. Requiring no heat treatment, the ferrite plating facilitates fabrication of ferrite film devices using non-heat-resistant substances (e.g.plastics, nano-sized multilayrs, etc.) as substrates. In this study we combined the ferrite plating with sonochemical technology to improve the crystallinity and magnetic properties of the plated films. Applying power ultrasound waves (19.5kHz, 600W) to an FeCl_2 aqueous solution at 70゜C,we successfully encapsulated polyacrylate spheres of two sizes, 0.25 mum and 4.5mum in average diameter, with ferrite coatings of a magnetite-maghemite mixed solution. This broke the previous lower limit (0.3mum) of the size of the particles to be encapsulated ; without application of the ultrasound waves, the ferrite coating became discontinuous or insular. Applying high frequency ultrasound waves (1.6MHz, 20W) and the above low frequency ultrasound waves simultaneously, Fe_3O_4 films were successfully improved in surface smoothness and solubility limit of Ni ions in films of NiZn ferrite (Ni_<3-x-y> Ni_x Zn_y O_4) was increased from x=0.35 to 0.42. The marked improvements are ascribed to "hot spots" and "micro-stirring" caused by collapse of cavitation bubbles in the sonicated aqueous solution.

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  • Study of magnetic nanoparticles and their applications

    Grant-in-Aid for Scientific Research 

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    Grant type:Competitive

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  • Study on Magnetic Recording Media

    Grant-in-Aid for Scientific Research 

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    Grant type:Competitive

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  • Study of microfabrication and spin transport for magnetic semiconductor

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    Grant type:Competitive

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  • 磁性半導体の微細加工とそのスピン伝導に関する研究

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    Grant type:Competitive

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  • 磁性ナノ粒子とその応用に関する研究

    科学研究費補助金 

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    Grant type:Competitive

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  • 磁気記録媒体に関する研究

    科学研究費補助金 

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    Grant type:Competitive

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