Updated on 2026/03/05

写真a

 
IWASA YOSHIHIRO
 
Organization
School of Materials and Chemical Technology Visiting Professor
Title
Visiting Professor
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Degree

  • 工学博士 ( 東京大学 )

Research Interests

  • デバイス

  • 有機材料

  • 炭素材料

  • カーボンナノチューブ

  • フラーレン

  • 物性

Research Areas

  • Natural Science / Magnetism, superconductivity and strongly correlated systems

  • Natural Science / Semiconductors, optical properties of condensed matter and atomic physics

Research History

  • RIKEN CEMS   Emergent Device Research Team   Team Leader

    2013

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  • The University of Tokyo   The Graduate School of Engineering, Department of Applied Physics   Professor

    2010

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  • RIKEN   Strong-Correlation Hybrid Materials Research Team, Correlated Electron Research Group (CERG), ASI   Team Leader

    2010 - 2013

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  • Tohoku University   IMR   Professor

    2001 - 2010

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  • Japan Advanced Institute of Science and Technology   Associate Professor

    1994 - 2001

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Professional Memberships

  • Electrochemical Society

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  • 応用物理学会

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  • 電気化学会(Electrochemical Society)

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  • フラーレン・ナノチューブ研究会

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  • アメリカ物理学会(American Physical Society)

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  • 日本物理学会

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  • フラーレン・ナノチューブ研究会幹事

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  • 放射光利用研究推進機構(財)高輝度光科学研究センター利用研究課題選定委員会分科会

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  • 東京大学物性研究所共同利用施設専門委員会委員

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Committee Memberships

  • 放射光利用研究推進機構(財)高輝度光科学研究センター利用研究課題選定委員会分科会   委員  

    2003   

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    Committee type:Academic society

    放射光利用研究推進機構(財)高輝度光科学研究センター利用研究課題選定委員会分科会

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  • フラーレン・ナノチューブ研究会幹事   幹事  

    2002   

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    Committee type:Academic society

    フラーレン・ナノチューブ研究会幹事

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Papers

  • Hot-Injection Synthesis of Monodisperse π-SnS Nanocrystals

    Thanyarat Phutthaphongloet, Ricky Dwi Septianto, Retno Miranti, Kiyohiro Adachi, Yuta Kubota, Daisuke Hashizume, Nobuhiro Matsushita, Yoshihiro Iwasa, Satria Zulkarnaen Bisri

    ACS Applied Nano Materials   8 ( 19 )   9702 - 9710   2025.5

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    Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society (ACS)  

    DOI: 10.1021/acsanm.5c00710

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  • High Volumetric Energy Density Supercapacitor of Additive-Free Quantum Dot Hierarchical Nanopore Structure

    Muhammad Alief Irham, Ricky Dwi Septianto, Retno Dwi Wulandari, Yutaka Majima, Ferry Iskandar, Yoshihiro Iwasa, Satria Zulkarnaen Bisri

    ACS Applied Materials and Interfaces   16 ( 19 )   24889 - 24898   2024.5

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    Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acsami.4c02517

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  • High Volumetric Energy Density Supercapacitor of Additive-Free Quantum Dot Hierarchical Nanopore Structure

    Muhammad Alief Irham, Ricky Dwi Septianto, Retno Dwi Wulandari, Yutaka Majima, Ferry Iskandar, Yoshihiro Iwasa, Satria Zulkarnaen Bisri

    ACS Applied Materials & Interfaces   16 ( 19 )   24889 - 24898   2024.5

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    Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society (ACS)  

    DOI: 10.1021/acsami.4c02517

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  • Electron transport in iodide-capped core@shell PbTe@PbS colloidal nanocrystal solids

    Retno Miranti, Ricky Dwi Septianto, Maria Ibanez, Maksym Kovalenko, Nobuhiro Matsushita, Yoshihiro Iwasa, Satria Zulkarnaen Bisri

    APPLIED PHYSICS LETTERS   117 ( 17 )   2020.10

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

    DOI: 10.1063/5.0025965

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  • Exceptionally High Electric Double Layer Capacitances of Oligomeric Ionic Liquids Reviewed

    Michio Matsumoto, Sunao Shimizu, Rina Sotoike, Masayoshi Watanabe, Yoshihiro Iwasa, Yoshimitsu Itoh, Takuzo Aida

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   139 ( 45 )   16072 - 16075   2017.11

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

    DOI: 10.1021/jacs.7b09156

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  • Quantum Griffiths Phase in ion-gated superconducting ZrNCl

    Saito Yu, Nojima Tsutomu, Iwasa Yoshihiro

    Meeting Abstracts of the Physical Society of Japan   71   1445 - 1445   2016

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    Language:Japanese   Publisher:The Physical Society of Japan  

    DOI: 10.11316/jpsgaiyo.71.2.0_1445

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  • Electron carrier-mediated room temperature ferromagnetism in anatase (ti,co) o 2

    Tomoteru Fukumura, Yoshinori Yamada, Kazunori Ueno, Hongtao Yuan, Hidekazu Shimotani, Yoshihiro Iwasa, L. I.N. Gu, Susumu Tsukimoto, Yuichi Ikuhara, Masashi Kawasaki

    SPIN   2 ( 4 )   2012.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:World Scientific Publishing Co. Pte Ltd  

    DOI: 10.1142/S2010324712300058

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  • Pressure effects on unoriented and oriented single-walled carbon nanotube films studied by infrared microscopy Reviewed

    C. A. Kuntscher, A. Abouelsayed, K. Thirunavukkuarasu, F. Hennrich, Y. Iwasa

    JOURNAL OF APPLIED PHYSICS   111 ( 11 )   2012.6

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

    DOI: 10.1063/1.4726214

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  • 27pTB-2 Ab initio calculation of High-density carrier accumulation states on ZnO by electric field

    Yoon,S. J, Okada,S, Shimotani,H, Arikawa,M, Otani,M, Iwasa,Y

    Meeting abstracts of the Physical Society of Japan   66 ( 1 )   879   2011.3

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:The Physical Society of Japan (JPS)  

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  • Raman spectroscopic study of the rare-earth fullerides Eu(6-x)Sr(x)C(60) Reviewed

    Arvanitidis J, Christofilos D, Kourouklis G. A, Paloumpi A, Papagelis K, Ves S, Iwasa Y, Prassides K

    Nanoscale   3 ( 6 )   2490 - 2493   2011

  • Ink-Jet Printing of a Single-Walled Carbon Nanotube Thin Film Transistor Reviewed

    Okimoto Haruya, Takenobu Taishi, Yanagi Kazuhiro, Miyata Yasumitsu, Kataura Hiromichi, Asano Takeshi, Iwasa Yoshihiro

    JAPANESE JOURNAL OF APPLIED PHYSICS   48 ( 6 )   2009.6

  • Synthesis, Phase Diagram, and Evolution of Electronic Properties in LixZrNCl Superconductors Reviewed

    Y. Taguchi, A. Kitora, T. Tekano, T. Kawabata, M. Hisakabe, Y. Iwasa

    FRONTIERS IN MATERIALS RESEARCH   10   93 - +   2008

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

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  • Copper phthalocyanine single-crystal field-effect transistors stable above 100°C Reviewed

    Koichi Yamada, Jun Takeya, Kunji Shigeto, Kazuhito Tsukagoshi, Yoshinobu Aoyagi, Yoshihiro Iwasa

    Materials Research Society Symposium Proceedings   937   126 - 131   2006

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  • Control of thin film transistor operations with polar self-assembled monolayers

    Y. Iwasa, T. Nishikawa, S. Kobayashi, T. Takenobu, T. Shimoda, T. Mitani, K. Kubozono

    Materials Research Society Symposium Proceedings   871   67 - 72   2005

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    Publishing type:Research paper (international conference proceedings)  

    DOI: 10.1557/proc-871-i3.3

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  • Raman study of prebure screening effects in double-wall carbon nanotubes

    J. Arvanitidis, D. Christofilos, K. Papagelis, K. S. Andrikopoulos, G. A. Kourouklis, S. Ves, T. Takenobu, Y. Iwasa, H. Kataura

    Joint 20th AIRAPT and 43rd EHPRG International Conference on High Pressure Science and Technology   2005

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:Karlsruhe Forschungszentrum Karlsruhe gmbH  

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  • High-pressure study of layered nitride superconductors Reviewed

    Y. Taguchi, M. Hisakabe, Y. Ohishi, S. Yamanaka, Y. Iwasa

    Physical Review B - Condensed Matter and Materials Physics   70 ( 10 )   1 - 104506   2004.9

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    DOI: 10.1103/PhysRevB.70.104506

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  • Structural transformation from single-wall to double-wall carbon nanotube bundles Reviewed

    Abe M, Kataura H, Kira H, Kodama T, Suzuki S, Achiba Y, Kato K, Takata M, Fujiwara A, Matsuda K, Maniwa Y

    PHYSICAL REVIEW B   68 ( 4 )   2003.7

  • Pressure-induced structural phase transition in fullerides doped with rare-earth metals Reviewed

    Dam Hieu Chi, Y. Iwasa, K. Uehara, T. Takenobu, T. Ito, T. Mitani, E. Nishibori, M. Takata, M. Sakata, Y. Ohishi, K. Kato, Y. Kubozono

    Physical Review B - Condensed Matter and Materials Physics   67 ( 9 )   2003.3

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    DOI: 10.1103/PhysRevB.67.094101

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  • Metal-insulator transition of donor-acceptor-type organic charge-transfer complex (BETS)2(Br2TCNQ): Site-selective NMR measurements Reviewed

    K. Hiraki, S. Furuta, T. Takahashi, R. Kondo, S. Kagoshima, T. Hasegawa, T. Mochida, Y. Iwasa

    Physical Review B - Condensed Matter and Materials Physics   66 ( 3 )   351041 - 351046   2002.7

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

    DOI: 10.1103/PhysRevB.66.035104

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  • Mixed-stack organic charge-transfer complexes with intercolumnar networks Reviewed

    T Hasegawa, T Mochida, R Kondo, S Kagoshima, Y Iwasa, T Akutagawa, T Nakamura, G Saito

    PHYSICAL REVIEW B   62 ( 15 )   10059 - 10066   2000.10

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

    DOI: 10.1103/PhysRevB.62.10059

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  • Structure and Raman scattering of Cs3C60 under high pressure Reviewed

    S Fujiki, K Kubozono, S Emura, Y Takabayashi, S Kashino, A Fujiwara, K Iskii, H Suematsu, Y Murakami, Y Iwasa, T Mitani, H Ogata

    PHYSICAL REVIEW B   62 ( 9 )   5366 - 5369   2000.9

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  • NMR evidence for Mott-Hubbard localization Reviewed

    H. Tou, Y. Maniwa, Y. Iwasa, H. Shimoda, T. Mitani

    Physical Review B - Condensed Matter and Materials Physics   62 ( 2 )   R775 - R778   2000

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    DOI: 10.1103/PhysRevB.62.R775

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  • Pressure dependence of superconductivity in the Na2Rb0.5Cs0.5C60 fulleride Reviewed

    CM Brown, T Takenobu, K Kordatos, K Prassides, Y Iwasa, K Tanigaki

    PHYSICAL REVIEW B   59 ( 6 )   4439 - 4444   1999.2

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  • Synthesis and properties of alkali-alkaline earth ternary superconducting fullerides. Reviewed

    IWASA Y, KAWAGUCHI M, TAGA S, TAKENOBU T, MITANI T, PRASSIDES K, BROWN CM

    RECENT ADVANCES IN THE CHEMISTRY AND PHYSICS OF FULLERENES AND RELATED MATERIALS, VOL 6   98   428 - 435   1998

  • Magnetism and dynamics of ammoniated K3C60 Reviewed

    BROWN CM, PRASSIDES K, IWASA Y, SHIMODA R

    PROCEEDINGS OF THE SYMPOSIUM ON RECENT ADVANCES IN THE CHEMISTRY AND PHYSICS OF FULLERENES AND RELATED MATERIALS, VOL 4   97   1224 - 1231   1997

  • Nature of one-dimensional excitons in polysilanes Reviewed

    T. Hasegawa, Y. Iwasa, T. Koda, H. Kishida, Y. Tokura, S. Wada, H. Tashiro, H. Tachibana, M. Matsumoto

    Physical Review B - Condensed Matter and Materials Physics   54 ( 16 )   11365 - 11374   1996

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

    DOI: 10.1103/PhysRevB.54.11365

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Books

  • Strong anisotropy in far-infrared absorption spectra of stretch-aligned single-walled carbon nanotubes

    Advanced Materials  2006 

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  • ナノマテリアル工学大系 第2巻 ナノ金属

    フジ・テクノシステム  2006 

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  • 環状・筒状超分子新素材の応用技術

    シーエムシー出版  2006 

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  • Strong anisotropy in far-infrared absorption spectra of stretch-aligned single-walled carbon nanotubes

    Advanced Materials  2006 

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  • 有機分子を内包したナノチューブ

    株式会社シーエムシー出版 環状・筒状超分子新素材の応用技術  2006 

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  • 有機トランジスタ材料の評価と応用

    シーエムシー出版  2005 

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  • 有機単結晶トランジスタと界面ドーピング

    有機トランジスタ材料の評価と応用  2005 

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  • フラーレン・ナノチューブネットワーク材料

    ナノマテリアル工学大系第2巻ナノ金属  2005 

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  • カーボンナノチューブー期待される材料開発ー

    シーエムシー出版  2001 

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  • Making Functional Materials with Nanotubes

    Materials Research Society  2001 

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  • Nanonetwork Materials

    American Institute of Physics  2001 

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  • Making Functional Materials with Nanotubes

    Materials Research Society  2001 

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  • 有機非線形光学材料の開発と応用

    シーエムシー出版  2001 

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  • Nanonetwork Materials

    American Institute of Physics  2001 

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  • Optical Properties of Low Dimensional Solid

    World Scientific  1996 

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  • Optical Properties of Low Dimensional Solid

    World Scientific  1996 

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MISC

  • Vortex-antivortex dynamics in ion-gated MoS2

    野島勉, 斎藤優, 板橋勇輝, 岩佐義宏, 岩佐義宏

    日本物理学会講演概要集(CD-ROM)   76 ( 1 )   2021

  • Wide range carrier density dependence of superconducting properties in ion-gated SrTiO3 surfaces

    大内拓, 清水直, 清水直, 岩佐義宏, 岩佐義宏, 野島勉

    日本物理学会講演概要集(CD-ROM)   75 ( 2 )   2020

  • Carrier density dependence of upper critical magnetic field in SrTiO3 electric-field-induced superconductors

    大内拓, 清水直, 清水直, 岩佐義宏, 岩佐義宏, 野島勉

    日本物理学会講演概要集(CD-ROM)   75 ( 1 )   2020

  • Critical Magnetic fields of MoS2 electric-field-induced superconductors

    野島勉, 大内拓, 板橋勇輝, 斎藤優, 岩佐義宏

    東北大学金属材料研究所強磁場超伝導材料研究センター年次報告   2018   2019

  • MoS2電界誘起超伝導体のゼロ磁場での動的相図

    斎藤優, 板橋勇輝, 野島勉, 岩佐義宏, 岩佐義宏

    日本物理学会講演概要集(CD-ROM)   74 ( 1 )   2019

  • SrTiO3電場誘起超伝導体における面内臨界磁場の増大とスピン軌道相互作用 II

    大内拓, 清水直, 清水直, 岩佐義宏, 岩佐義宏, 野島勉

    日本物理学会講演概要集(CD-ROM)   74 ( 2 )   2019

  • NdSe2原子層超伝導薄膜の上部臨界磁場

    野島勉, 大内拓, 松岡秀樹, 中野匡規, 岩佐義宏, 岩佐義宏

    東北大学金属材料研究所強磁場超伝導材料研究センター年次報告   2017   2018

  • SrTiO3電場誘起超伝導体における高ドープ領域での面内臨界磁場の増大

    大内拓, 清水直, 岩佐義宏, 岩佐義宏, 野島勉

    日本物理学会講演概要集(CD-ROM)   73 ( 1 )   2018

  • SrTiO3電場誘起超伝導体における面内臨界磁場の増大とスピン軌道相互作用

    大内拓, 清水直, 岩佐義宏, 岩佐義宏, 野島勉

    日本物理学会講演概要集(CD-ROM)   73 ( 2 )   2018

  • FeSe極薄膜の熱電効果

    清水直, 塩貝純一, 野島勉, 塚崎敦, 岩佐義宏, 岩佐義宏

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   78th   2017

  • FeSe超薄膜の熱電効果

    清水直, 塩貝純一, 野島勉, 塚崎敦, 岩佐義宏, 岩佐義宏

    日本物理学会講演概要集(CD-ROM)   72 ( 1 )   2017

  • 高結晶性2次元超伝導体の量子相転移

    斎藤優, 野島勉, 岩佐義宏, 岩佐義宏

    日本物理学会講演概要集(CD-ROM)   72 ( 2 )   2017

  • 電場誘起超伝導体MoS2の上部臨界磁場

    野島勉, 大内拓, 斎藤優, 岩佐義宏, 岩佐義宏

    東北大学金属材料研究所強磁場超伝導材料研究センター年次報告   2016   2017

  • SrTiO3電場誘起超伝導のキャリア蓄積層厚さ

    上野和紀, 上野和紀, 野島勉, 米澤進吾, 川崎雅司, 川崎雅司, 川崎雅司, 前野悦輝, 岩佐義宏, 岩佐義宏

    応用物理学会学術講演会講演予稿集(CD-ROM)   72nd   2011

  • The Disorder-Free Non-BCS Superconductor Cs3C60 Emerges from an Antiferromagnetic Insulator Parent State

    Yasuhiro Takabayashi, Alexey Y. Ganin, Peter Jeglic, Denis Arcon, Takumi Takano, Yoshihiro Iwasa, Yasuo Ohishi, Masaki Takata, Nao Takeshita, Kosmas Prassides, Matthew J. Rosseinsky

    SCIENCE   323 ( 5921 )   1585 - 1590   2009.3

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  • Ink-Jet Printing of Carbon Nanotube Thin-Film Transistors on Flexible Plastic Substrates

    Taishi Takenobu, Noriko Miura, Sheng-Yi Lu, Haruya Okimoto, Takeshi Asano, Masashi Shiraishi, Yoshihiro Iwasa

    APPLIED PHYSICS EXPRESS   2 ( 2 )   025005   2009.2

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  • KTaO3をチャネルとした電気二重層トランジスタ

    上野和紀, 赤塚俊彦, 中村慎太郎, 下谷秀和, YUAN H.T., YUAN H.T., 野島勉, 木村憲彰, 青木晴善, 岩佐義宏, 岩佐義宏, 川崎雅司, 川崎雅司, 川崎雅司

    応用物理学会学術講演会講演予稿集   70th ( 2 )   2009

  • Optical properties of layered superconductor LixZrNCl

    T. Takano, A. Kitora, Y. Taguchi, Y. Iwasa

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   69 ( 12 )   3089 - 3092   2008.12

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  • Enhancement of carrier hopping by doping in single walled carbon nanotube films

    Takumi Takano, Taishi Takenobu, Yoshihiro Iwasa

    Journal of the Physical Society of Japan   77 ( 12 )   124709   2008.12

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  • Enhancement of Carrier Hopping by Doping in Single Walled Carbon Nanotube Films

    Takumi Takano, Taishi Takenobu, Yoshihiro Iwasa

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 12 )   124709   2008.12

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  • Electric-field-induced superconductivity in an insulator

    K. Ueno, S. Nakamura, H. Shimotani, A. Ohtomo, N. Kimura, T. Nojima, H. Aoki, Y. Iwasa, M. Kawasaki

    Nature Materials   7 ( 11 )   855 - 858   2008.11

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    Language:English   Publisher:Nature Publishing Group  

    DOI: 10.1038/nmat2298

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  • Electric-field-induced superconductivity in an insulator

    K. Ueno, S. Nakamura, H. Shimotani, A. Ohtomo, N. Kimura, T. Nojima, H. Aoki, Y. Iwasa, M. Kawasaki

    NATURE MATERIALS   7 ( 11 )   855 - 858   2008.11

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  • Ambipolar, single-component, metal-organic thin-film transistors with high and balanced hole and electron mobilities

    Shin-ichiro Noro, Taishi Takenobu, Yoshihiro Iwasa, Ho-Chol Chang, Susumu Kitagawa, Tomoyuki Akutagawa, Takayoshi Nakamura

    ADVANCED MATERIALS   20 ( 18 )   3399 - +   2008.9

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  • Blue-light-emitting ambipolar field-effect transistors using an organic single crystal of 1,4-Bis(4-methylstyryl)benzene

    Hajime Nakanotani, Ryota Kabe, Masayuki Yahiro, Taishi Takenobu, Yoshihiro Iwasa, Chihaya Adachi

    APPLIED PHYSICS EXPRESS   1 ( 9 )   91801   2008.9

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  • Effect of postannealing on the performance of pentacene single-crystal ambipolar transistors

    Taishi Takenobu, Kazuhiro Watanabe, Yohei Yomogida, Hidekazu Shimotani, Yoshihiro Iwasa

    APPLIED PHYSICS LETTERS   93 ( 7 )   073301   2008.8

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  • p-type field-effect transistor of NiO with electric double-layer gating

    Hidekazu Shimotani, Hirotaka Suzuki, Kazunori Ueno, Masashi Kawasaki, Yoshihiro Iwasa

    APPLIED PHYSICS LETTERS   92 ( 24 )   242107   2008.6

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  • Interlayer-spacing dependence of T(c) in Li(x)M(y)HfNCl (M : molecule) superconductors

    T. Takano, T. Kishiume, Y. Taguchi, Y. Iwasa

    PHYSICAL REVIEW LETTERS   100 ( 24 )   247005   2008.6

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  • Low-energy excitations in electron-doped metal phthalocyanines

    M. Filibian, P. Carretta, T. Miyake, Y. Taguchi, Y. Iwasa, G. Zoppellaro, M. Ruben

    PHYSICA B-CONDENSED MATTER   403 ( 5-9 )   1523 - 1525   2008.4

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  • Mobility and dynamics of charge carriers in Rubrene single crystals studied by flash-photolysis microwave conductivity and optical spectroscopy

    Akinori Saeki, Shu Seki, Taishi Takenobu, Yoshihiro Iwasa, Seiichi Tagawa

    ADVANCED MATERIALS   20 ( 5 )   920 - +   2008.3

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  • Modulation-doped-semiconductorlike behavior manifested in magnetotransport measurements of Li(x)ZrNCl layered superconductors

    T. Takano, A. Kitora, Y. Taguchi, Y. Iwasa

    PHYSICAL REVIEW B   77 ( 10 )   104518   2008.3

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  • Quantitative analysis of electronic transport through weakly coupled metal/organic interfaces

    A. S. Molinari, I. Gutierrez Lezama, P. Parisse, T. Takenobu, Y. Iwasa, A. F. Morpurgo

    APPLIED PHYSICS LETTERS   92 ( 13 )   133303   2008.3

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  • Magnetic-field dependence of the ferroelectric polarization and spin-lattice coupling in multiferroic MnWO(4)

    K. Taniguchi, N. Abe, H. Sagayama, S. Ohtani, T. Takenobu, Y. Iwasa, T. Arima

    PHYSICAL REVIEW B   77 ( 6 )   064408   2008.2

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  • High current density in light-emitting transistors of organic single crystals

    Taishi Takenobu, Satria Zulkarnaen Bisri, Tetsuo Takahashi, Masayuki Yahiro, Chihaya Adachi, Yoshihiro Iwasa

    PHYSICAL REVIEW LETTERS   100 ( 6 )   066601   2008.2

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  • High current density in light-emitting transistors of organic single crystals

    Phys. Rev. Lett.   100 ( 6 )   066601   2008

  • Effect of postannealing on the performance of pentacene single-crystal ambipolar transistors

    Appl. Phys. Lett.   93 ( 7 )   073301   2008

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  • Effects of gate dielectrics and metal electrodes on air-stable n-channel perylene tetracarboxylic dianhydride single-crystal field-effect transistors

    Koichi Yamada, J. Takeya, T. Takenobu, Y. Iwasa

    Applied Physics Letters   92 ( 25 )   253311   2008

  • Fabrication of ambipolar light-emitting transistor using high-photoluminescent organic single crystal

    Proceedings of SPIE - The International Society for Optical Engineering   6999   69990Z   2008

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  • Structural support of the external tubes in double-wall carbon nanotubes

    J. Arvanitidis, D. Christofilos, G. A. Kourouklis, S. Ves, T. Takenobu, Y. Iwasa, H. Kataura

    HIGH PRESSURE RESEARCH   28 ( 4 )   591 - 595   2008

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  • One-dimensional bromo-bridged Ni-III complexes [Ni(S,S-bn)(2)Br]Br-2 (S,S-bn=2S,3S-diaminobutane): Synthesis, physical properties, and electrostatic carrier doping

    Shinya Takaishi, Masahiro Yamashita, Hiroyuki Matsuzaki, Hiroshi Okamoto, Hisaaki Tanaka, Shin-ichi Kuroda, Atsushi Goto, Tadashi Shimizu, Taishi Takenobu, Yoshihiro Iwasa

    CHEMISTRY-A EUROPEAN JOURNAL   14 ( 2 )   472 - 477   2008

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  • Enhancement of Carrier Hopping by Doping in Single Walled Carbon Nanotube Films

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 12 )   124709   2008

  • Blue-light-emitting ambipolar field-effect transistors using an organic single crystal of 1,4-Bis(4-methylstyryl)benzene

    Appl. Phys. Express   1 ( 9 )   91801   2008

  • Fabrication of ambipolar light-emitting transistor using high-photoluminescent organic single crystal

    Satria Zulkarnaen Bisri, Taishi Takenobu, Yohei Yomogida, Takeshi Yamao, Masayuki Yahiro, Shu Hotta, Chihaya Adachi, Yoshihiro Iwasa

    ORGANIC OPTOELECTRONICS AND PHOTONICS III   6999   69990Z   2008

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  • Polarization reversal in multiferroic TbMnO3 with a rotating magnetic field direction

    N. Abe, K. Taniguchi, S. Ohtani, T. Takenobu, Y. Iwasa, T. Arima

    Physical Review Letters   99 ( 22 )   Art.No.227206   2007.11

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  • Pressure-induced phenomena in single-walled carbon nanotubes

    C. A. Kuntscher, K. Thirunavukkuarasu, A. Pekker, K. Kamaras, F. Hennrich, M. Kappes, Y. Iwasa

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   244 ( 11 )   3982 - 3985   2007.11

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  • Polarization reversal in multiferroic TbMnO(3) with a rotating magnetic field direction

    N. Abe, K. Taniguchi, S. Ohtani, T. Takenobu, Y. Iwasa, T. Arima

    PHYSICAL REVIEW LETTERS   99 ( 22 )   Art.No.227206   2007.11

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  • Tube encapsulation effects in various carbon nanotube systems

    D. Christofilos, J. Arvanitidis, E. Efthimiopoulos, X. Zha, Y. Ando, T. Takenobu, Y. Iwasa, H. Kataura, S. Ves, G. A. Kourouklis

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   244 ( 11 )   4082 - 4085   2007.11

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  • High pressure Raman study of the second-order vibrational modes of single- and double-walled carbon nanotubes

    K. Papagelis, K. S. Andrikopoulos, J. Arvanitidis, D. Christofilos, C. Galiotis, T. Takenobu, Y. Iwasa, H. Kataura, S. Ves, G. A. Kourouklis

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   244 ( 11 )   4069 - 4073   2007.11

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  • Structural study of single-walled carbon nanotube films doped by a solution method

    Taishi Takenobu, Tetsuo Takahashi, Nima Akima, Masashi Shiraishi, Hiromichi Kataura, Yoshihiro Iwasa

    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY   7 ( 10 )   3533 - 3536   2007.10

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  • Identification of inner and outer shells of double-wall carbon nanotubes using high-pressure Raman spectroscopy

    D. Christofilos, J. Arvanitidis, G. A. Kourouklis, S. Ves, T. Takenobu, Y. Iwasa, H. Kataura

    PHYSICAL REVIEW B   76 ( 11 )   113402   2007.9

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  • Isotope effect in LixZrNCl superconductors

    Y. Taguchi, T. Kawabata, T. Takano, A. Kitora, K. Kato, M. Takata, Y. Iwasa

    PHYSICAL REVIEW B   76 ( 6 )   064508   2007.8

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  • Insulator-to-metal transition in ZnO by electric double layer gating

    Hidekazu Shimotani, Haruhiko Asanuma, Atsushi Tsukazaki, Akira Ohtomo, Masashi Kawasaki, Yoshihiro Iwasa

    APPLIED PHYSICS LETTERS   91 ( 8 )   082106-082106-3   2007.8

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  • Ambipolar light-emitting transistors of a tetracene single crystal

    Tetsuo Takahashi, Taishi Takenobu, Jun Takeya, Yoshihiro Iwasa

    Advanced Functional Materials   17 ( 10 )   1623 - 1628   2007.7

  • Ambipolar field-effect transistor of high photoluminescent material tetraphenylpyrene (TPPy) single crystal

    Satria Zulkarnaen Bisri, Tetsuo Takahashi, Taishi Takenobu, Masayuki Yahiro, Chihaya Adachi, Yoshihiro Iwasa

    Japanese Journal of Applied Physics, Part 2: Letters   46 ( 20-24 )   L596 - L598   2007.6

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  • Electric double layer transistor of organic semiconductor crystals in a four-probe configuration

    Hidekazu Shimotani, Haruhiko Asanuma, Yoshihiro Iwasa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   46 ( 6A )   3613 - 3617   2007.6

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  • Suppression of current hysteresis in carbon nanotube thin-film transistors

    Kazuhito Tsukagoshi, Masahiro Sekiguchi, Yoshinobu Ayagi, Takayoshi Kanbara, Taishi Takenobu, Yoshihiro Iwasa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   46 ( 20-24 )   L571 - L573   2007.6

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  • In-crystal and surface charge transport of electric-field-induced carriers in organic single-crystal semiconductors

    J. Takeya, J. Kato, K. Hara, M. Yamagishi, R. Hirahara, K. Yamada, Y. Nakazawa, S. Ikehata, K. Tsukagoshi, Y. Aoyagi, T. Takenobu, Y. Iwasa

    Physical Review Letters   98 ( 19 )   Art.No.196804   2007.5

  • One-dimensional magnetism and doping effects in metal-phthalocyanine systems

    Y. Taguchi, T. Miyake, S. Margadonna, K. Kato, K. Prassides, Y. Iwasa

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   310 ( 2 )   1229 - 1230   2007.3

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  • Probing electron-phonon interaction in LixZrNCl superconductors by Raman scattering

    A. Kitora, Y. Taguchi, Y. Iwasa

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   76 ( 2 )   Art.No.023706   2007.2

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  • Probing electron-phonon interaction in LixZrNCl superconductors by Raman scattering

    A. Kitora, Y. Taguchi, Y. Iwasa

    Journal of the Physical Society of Japan   76 ( 2 )   Art.No.023706   2007.2

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  • Low-energy excitations in the electron-doped metal phthalocyanine Li0.5MnPc from Li-7 and H-1 NMR

    M. Filibian, P. Carretta, T. Miyake, Y. Taguchi, Y. Iwasa

    PHYSICAL REVIEW B   75 ( 8 )   085107   2007.2

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  • Second-order Raman study of double-wall carbon nanotubes under high pressure

    K. Papagelis, J. Arvanitidis, D. Christofilos, K. S. Andrikopoulos, T. Takenobu, Y. Iwasa, H. Kataura, S. Ves, G. A. Kourouklis

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   244 ( 1 )   116 - 120   2007.1

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  • Magnetic ordering in the ammoniated alkali fullerides (NH3)K3-xRbxC60(x=2,3)

    Journal of Physics-Condensed Matter   19 ( 38 )   Art.No. 386235   2007

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  • 電気二重層トランジスタを用いたSrTiO3単結晶の絶縁体-超伝導転移

    上野和紀, 中村慎太郎, 下谷秀和, 大友明, 野島勉, 木村憲彰, 青木晴善, 岩佐義宏, 岩佐義宏, 川崎雅司, 川崎雅司

    応用物理学会学術講演会講演予稿集   68th ( 2 )   2007

  • Ambipolar field-effect transistor of high photoluminescent material tetraphenylpyrene(TPPy) single crystal

    Japanese Journal of Applied Physics Part 2-Letters&Express Letters   46 ( 20-24 )   L596-L598   2007

  • Magnetic ordering in the ammoniated alkali fullerides (NH3)K3-xRbxC60(x=2,3)

    Journal of Physics-Condensed Matter   19 ( 38 )   Art.No. 386235   2007

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  • Effect of metal electrodes on rubrene single-crystal transistors

    Taishi Takenobu, Tetsuo Takahashi, Jun Takeya, Yoshihiro Iwasa

    Applied Physics Letters   90 ( 1 )   2007

  • Electrical conducting bis(oxalato)platinate complex with direct connection of CuII ions

    Chihiro Yamamoto, Hiroyuki Nishikawa, Masayuki Nihei, Takuya Shiga, Masato Hedo, Yoshiya Uwatoko, Hiroshi Sawa, Hiroshi Kitagawa, Yasujiro Taguchi, Yoshihiro Iwasa, Hiroki Oshio

    Inorganic Chemistry   45 ( 25 )   10270 - 10276   2006.12

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  • Spatial extent of wave functions of gate-induced hole carriers in pentacene field-effect devices as investigated by electron spin resonance

    Kazuhiro Marumoto, Shin-ichi Kuroda, Taishi Takenobu, Yoshihiro Iwasa

    PHYSICAL REVIEW LETTERS   97 ( 25 )   256603   2006.12

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  • Electrical conducting bis(oxalato)platinate complex with direct connection of Cu-II ions

    Chihiro Yamamoto, Hiroyuki Nishikawa, Masayuki Nihei, Takuya Shiga, Masato Hedo, Yoshiya Uwatoko, Hiroshi Sawa, Hiroshi Kitagawa, Yasujiro Taguchi, Yoshihiro Iwasa, Hiroki Oshio

    INORGANIC CHEMISTRY   45 ( 25 )   10270 - 10276   2006.12

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  • Bonding nature and structural phase transition in fullerene based nanomaterials

    Dam Hieu Chi, Y. Iwasa, M. Takata

    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY   6 ( 12 )   3888 - 3892   2006.12

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  • Potassium phthalocyanine, KPc: One-dimensional molecular stacks bridged by K+ ions

    Serena Margadonna, Kosmas Prassides, Yoshihiro Iwasa, Yasujiro Taguchi, Monica F. Craciun, Sven Rogge, Alberto F. Morpurgo

    INORGANIC CHEMISTRY   45 ( 26 )   10472 - 10478   2006.12

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  • Bonding nature and structural phase transition in fullerene based nanomaterials

    Dam Hieu Chi, Y. Iwasa, M. Takata

    Journal of Nanoscience and Nanotechnology   6 ( 12 )   3888 - 3892   2006.12

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  • Electrical conducting bis(oxalato)platinate complex with direct connection of Cu-II ions

    Chihiro Yamamoto, Hiroyuki Nishikawa, Masayuki Nihei, Takuya Shiga, Masato Hedo, Yoshiya Uwatoko, Hiroshi Sawa, Hiroshi Kitagawa, Yasujiro Taguchi, Yoshihiro Iwasa, Hiroki Oshio

    INORGANIC CHEMISTRY   45 ( 25 )   10270 - 10276   2006.12

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  • Spatial extent of wave functions of gate-induced hole carriers in pentacene field-effect devices as investigated by electron spin resonance

    Kazuhiro Marumoto, Shin-ichi Kuroda, Taishi Takenobu, Yoshihiro Iwasa

    PHYSICAL REVIEW LETTERS   97 ( 25 )   Art.No.256603   2006.12

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  • Optical evidence of Stark effect in single-walled carbon nanotube transistors

    Taishi Takenobu, Yuji Murayama, Yoshihiro Iwasa

    APPLIED PHYSICS LETTERS   89 ( 26 )   Art.No.263510-263510   2006.12

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  • Optical observation of carrier accumulation in single-walled carbon nanotube transistors

    Taishi Takenobu, Yuji Murayama, Masashi Shiraishi, Yoshihiro Iwasa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   45 ( 42-45 )   L1190 - L1192   2006.11

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  • Polymer ring formation by electron/hole injection from an STM tip into a C-60 close-packed layer

    Ryo Nouchi, Kosuke Masunari, Toshio Ohta, Yoshihiro Kubozono, Yoshihiro Iwasa

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   243 ( 13 )   3017 - 3020   2006.11

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  • Ring of C-60 polymers formed by electron or hole injection from a scanning tunneling microscope tip

    Ryo Nouchi, Kosuke Masunari, Toshio Ohta, Yoshihiro Kubozono, Yoshihiro Iwasa

    PHYSICAL REVIEW LETTERS   97 ( 19 )   Art.No.196101   2006.11

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  • Rubrene single crystal field-effect transistor with epitaxial BaTiO3 high-k gate insulator

    Nobuya Hiroshiba, Ryotaro Kumashiro, Katsumi Tanigaki, Taishi Takenobu, Yoshihiro Iwasa, Kenta Kotani, Iwao Kawayama, Masayoshi Tonouchi

    APPLIED PHYSICS LETTERS   89 ( 15 )   Art.No.152110   2006.10

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  • Ferroelectric polarization flop in a frustrated magnet MnWO4 induced by a magnetic field

    K. Taniguchi, N. Abe, T. Takenobu, Y. Iwasa, T. Arima

    PHYSICAL REVIEW LETTERS   97 ( 9 )   Art.No.097203   2006.9

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  • Increase in T-c upon reduction of doping in LixZrNCl superconductors

    Y. Taguchi, A. Kitora, Y. Iwasa

    PHYSICAL REVIEW LETTERS   97 ( 10 )   Art.No.107001   2006.9

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  • Duality in an electron-doped ZrNCl superconductor as revealed by specific heat measurement

    Y. Taguchi, A. Kitora, M. Hisakabe, Y. Iwasa

    PHYSICA B-CONDENSED MATTER   383 ( 1 )   67 - 70   2006.8

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  • Band structure modulation by carrier doping in random-network carbon nanotube transistors

    Shuichi Nakamura, Megumi Ohishi, Masashi Shiraishi, Taishi Takenobu, Yoshihiro Iwasa

    APPLIED PHYSICS LETTERS   89 ( 1 )   Art.No. 013112   2006.7

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  • Specific heat capacity and magnetic susceptibility of superconducting Ba24Si100

    Takeshi Rachi, Katsumi Tanigaki, Ryotaro Kumashiro, Kensuke Kobayashi, Harukazu Yoshino, Keizo Murata, Hiroshi Fukuoka, Syoji Yamanaka, Hidekazu Shimotani, Taishi Takenobu, Yoshihiro Iwasa, Takahiko Sasaki, Norio Kobayashi, Yuji Miyazaki, Kazuya Saito

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   67 ( 5-6 )   1334 - 1337   2006.5

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  • Fabrication of field-effect transistor devices with fullerodendron by solution process

    H Kusai, T Nagano, K Imai, Y Kubozono, Y Sako, Y Takaguchi, A Fujiwara, N Akima, Y Iwasa, S Hino

    APPLIED PHYSICS LETTERS   88 ( 17 )   Art.No. 173509   2006.4

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  • Gigantic optical stark effect and ultrafast relaxation of excitons in single-walled carbon nanotubes

    A Maeda, S Matsumoto, H Kishida, T Takenobu, Y Iwasa, H Shimoda, O Zhou, M Shiraishi, H Okamoto

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   75 ( 4 )   Art.No.043709   2006.4

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  • Raman study of metallic carbon nanotubes at elevated pressure

    D. Christofilos, J. Arvanitidis, C. Tzampazis, K. Papagelis, T. Takenobu, Y. Iwasa, H. Kataura, C. Lioutas, S. Ves, G. A. Kourouklis

    DIAMOND AND RELATED MATERIALS   15 ( 4-8 )   1075 - 1079   2006.4

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  • Charge transport of copper phthalocyanine single-crystal field-effect transistors stable above 100 °c

    Koichi Yamada, J. Takeya, K. Shigeto, K. Tsukagoshi, Y. Aoyagi, Y. Iwasa

    Applied Physics Letters   88 ( 12 )   122110   2006.3

  • Synthesis, structure, and magnetic properties of Li-doped manganese-phthalocyanine, Li-x[MnPc] (0 <= x <= 4)

    Y Taguchi, T Miyake, S Margadonna, K Kato, K Prassides, Y Iwasa

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   128 ( 10 )   3313 - 3323   2006.3

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  • Magnetic correlation in BETS2(Cl(2)TCNQ)

    Y. Takano, K. Hiraki, T. Takahashi, R. Kondo, S. Kagoshima, T. Hasegawa, T. Mocihda, Y. Iwasa

    JOURNAL OF LOW TEMPERATURE PHYSICS   142 ( 3-4 )   647 - 650   2006.2

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  • Electronic transport through electron-doped metal ppthalocyanine materials

    MF Craciun, S Rogge, MJL den Boer, S Margadonna, K Prassides, Y Iwasa, AF Morpurgo

    ADVANCED MATERIALS   18 ( 3 )   320 - +   2006.2

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  • Gate capacitance in electrochemical transistor of single-walled carbon nanotube

    H Shimotani, T Kanbara, Y Iwasa, K Tsukagoshi, Y Aoyagi, H Kataura

    APPLIED PHYSICS LETTERS   88 ( 7 )   073104-073104   2006.2

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  • Contact resistance modulation in carbon nanotube devices investigated by four-probe experiments

    T Kanbara, T Takenobu, T Takahashi, Y Iwasa, K Tsukagoshi, Y Aoyagi, H Kataura

    APPLIED PHYSICS LETTERS   88 ( 5 )   053118-053118   2006.1

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  • High-performance transparent flexible transistors using carbon nanotube films

    T Takenobu, T Takahashi, T Kanbara, K Tsukagoshi, Y Aoyagi, Y Iwasa

    APPLIED PHYSICS LETTERS   88 ( 3 )   033511-033511   2006.1

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  • Organic single crystal transistors: Interface modification with SAMs and double gate structure

    Molecular Crystals and Liquid Crystals   455   277-285, SUPPL 2P - 285   2006

  • Organic single crystal transistors: Interface modification with SAMs and double gate structure

    IWASA Yoshihiro, ASANUMA Haruhiko, SHIMOTANI Hidekazo, TAKENOBU Taishi, IWASA Yoshihiro, ASANUMA Haruhiko, SHIMOTANI Hidekazo, TAKENOBU Taishi, NISHIKAWA Takao, TAKEYA Jun

    Molecular Crystals and Liquid Crystals   455   277-285, SUPPL 2P - 285   2006

  • Ambipolar organic field-effect transistors using carbon nanotube films

    Applied Physics Letters   88 ( 3 )   033505-033505   2006

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  • Optical Stark Effect of Exciton in Semiconducting Single-Walled Carbon Nanotubes

    Japanese Journal of Applied Physics   45 ( 20 )   L513-L515   2006

  • Comment on "Large optical nonlinearity of semiconducting single-walled carbon nanotubes under resonant excitations"- Okamoto et al. reply

    Physical Review Letters   96 ( 1 )   019706-019706   2006

  • Effects of growth conditions on structure of organosilane monolayers on SiO2 substrates

    N Yoshimoto, M Maruyama, T Nishikawa, Y Iwasa, T Shimoda, S Ogawa

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   445   49 - 55   2006

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  • Electrolyte-gated charge accumulation in organic single crystals

    Hidekazu Shimotani, Haruhiko Asanuma, Jun Takeya, Yoshihiro Iwasa

    Applied Physics Letters   89 ( 20 )   Art.No.203501   2006

  • Optical evidence of Stark effect in single-walled carbon nanotube transistors

    Appl. Phys. Lett.   89   263510   2006

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  • 有機分子を内包したナノチューブ

    固体物理   41 ( 1 )   53 - 60   2006

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  • フラーレン材料の電界効果トランジスタへの応用と展望

    (株)エヌ・ティー・エス 未来材料   第6 ( 7 )   24 - 31   2006

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  • Optical evidence of Stark effect in single-walled carbon nanotube transistors

    Appl. Phys. Lett.   89   263510   2006

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  • Basic understanding of organic field effect transistors and their opportunities

    信学技報   ED2006-67   55 - 58   2006

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  • Ambipolar organic field-effect transistors using carbon nanotube films

    Applied Physics Letters   88 ( 3 )   033505-033505   2006

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  • Optical Stark Effect of Exciton in Semiconducting Single-Walled Carbon Nanotubes

    Japanese Journal of Applied Physics   45 ( 20 )   L513-L515   2006

  • Comment on "Large optical nonlinearity of semiconducting single-walled carbon nanotubes under resonant excitations"- Okamoto et al. reply

    Physical Review Letters   96 ( 1 )   019706-019706   2006

  • Basic understanding of organic field effect transistors and their opportunities

    信学技報   ED2006-67   55 - 58   2006

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  • Hall effect of quasi-hole gas in organic single-crystal transistors

    Jun Takeya, Kazuhito Tsukagoshi, Yoshinobu Aoyagi, Taishi Takenobu, Yoshihiro Iwasa

    Japanese Journal of Applied Physics, Part 2: Letters   44 ( 46-49 )   L1393 - L1396   2005.11

  • Double-wall carbon nanotubes under pressure: Probing the response of individual tubes and their intratube correlation

    J. Arvanitidis, D. Christofilos, K. Papagelis, T. Takenobu, Y. Iwasa, H. Kataura, S. Ves, G. A. Kourouklis

    Physical Review B - Condensed Matter and Materials Physics   72 ( 19 )   193411   2005.11

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  • Suppression of the unconventional metallic behavior by gate voltage in MWNT device

    T Kanbara, Y Iwasa, K Tsukagoshi, Y Aoyagi

    PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES   29 ( 3-4 )   698 - 701   2005.11

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  • Superconductivity and physical properties of Ba24Si100 determined from electric transport, specific-heat capacity, and magnetic susceptibility measurements

    Takeshi Rachi, Harukazu Yoshino, Ryotaro Kumashiro, Masaki Kitajima, Kensuke Kobayashi, Keiichi Yokogawa, Keizo Murata, Noriaki Kimura, Haruyoshi Aoki, Hiroshi Fukuoka, Syoji Yamanaka, Hidekazu Shimotani, Taishi Takenobu, Yoshihiro Iwasa, Takahiko Sasaki, Norio Kobayashi, Yuji Miyazaki, Kazuya Saito, Fangzhun Guo, Keisuke Kobayashi, Keiichi Osaka, Kenichi Kato, Masaki Takata, Katsumi Tanigaki

    Physical Review B - Condensed Matter and Materials Physics   72 ( 14 )   144504 - 144504   2005.10

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  • Superconductivity and physical properties of Ba24Si100 determined from electric transport, specific-heat capacity, and magnetic susceptibility measurements

    T Rachi, H Yoshino, R Kumashiro, M Kitajima, K Kobayashi, K Yokogawa, K Murata, N Kimura, H Aoki, H Fukuoka, S Yamanaka, H Shimotani, T Takenobu, Y Iwasa, T Sasaki, N Kobayashi, Y Miyazaki, K Saito, FZ Guo, K Kobayashi, K Osaka, K Kato, M Takata, K Tanigaki

    PHYSICAL REVIEW B   72 ( 14 )   144504 - 144504   2005.10

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  • Anomalously large electron-phonon coupling constant in layered nitride superconductors as revealed by high-pressure experiments

    M Hisakabe, Y Taguchi, Y Ohishi, S Yamanaka, Y Iwasa

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   426   482 - 486   2005.10

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  • Control of carrier density by a solution method in carbon-nanotube devices

    T Takenobu, T Kanbara, N Akima, T Takahashi, M Shiraishi, K Tsukagoshi, H Kataura, Y Aoyagi, Y Iwasa

    ADVANCED MATERIALS   17 ( 20 )   2430 - +   2005.10

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  • Control of injected carriers in tetracyano-p-quinodimethane encapsulated carbon nanotube transistors

    M Shiraishi, S Nakamura, T Fukao, T Takenobu, H Kataura, Y Iwasa

    APPLIED PHYSICS LETTERS   87 ( 9 )   093107-093107   2005.8

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  • B-11 NMR study of pure and lightly carbon-doped MgB2 superconductors

    M Karayanni, G Papavassiliou, M Pissas, M Fardis, K Papagelis, K Prassides, T Takenobu, Y Iwasa

    JOURNAL OF SUPERCONDUCTIVITY   18 ( 4 )   521 - 528   2005.8

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  • Metal-organic thin-film transistor (MOTFT) based on bis(o-diiminobenzosemiquinonate) nickel(II) complex

    S Noro, HC Chang, T Takenobu, Y Murayama, T Kanbara, T Aoyama, T Sassa, T Wada, D Tanaka, S Kitagawa, Y Iwasa, T Akutagawa, T Nakamura

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   127 ( 28 )   10012 - 10013   2005.7

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  • Upper critical field in the electron-doped layered superconductor ZrNCl0.7: Magnetoresistance studies

    H Tou, YJ Tanaka, M Sera, Y Taguchi, T Sasaki, Y Iwasa, L Zhu, S Yamanaka

    PHYSICAL REVIEW B   72 ( 2 )   020501-020501   2005.7

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  • Specific heat measurement of the layered nitride superconductor LixZrNCl

    Y. Taguchi, M. Hisakabe, Y. Iwasa

    Physical Review Letters   94 ( 21 )   217002 - 217002   2005.6

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  • Metallic phase in the metal-intercalated higher fullerene Rb8.8(7)C84

    Y Rikiishi, Y Kashino, H Kusai, Y Takabayashi, E Kuwahara, Y Kubozono, T Kambe, T Takenobu, Y Iwasa, N Mizorogi, S Nagase, S Okada

    PHYSICAL REVIEW B   71 ( 22 )   224118 - 224118   2005.6

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  • Specific heat measurement of the layered nitride superconductor LixZrNCl

    Y Taguchi, M Hisakabe, Y Iwasa

    PHYSICAL REVIEW LETTERS   94 ( 21 )   217002 - 217002   2005.6

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  • High energy-resolution electron energy-loss spectroscopy study of the electronic structure Of C-60 polymer crystals

    M Terauchi, S Nishimura, Y Iwasa

    JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA   143 ( 2-3 )   167 - 172   2005.5

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  • Ambipolar operation of fullerene field-effect transistors by semiconductor/metal interface modification

    T Nishikawa, S Kobayashi, T Nakanowatari, T Mitani, T Shimoda, Y Kubozono, G Yamamoto, H Ishii, M Niwano, Y Iwasa

    JOURNAL OF APPLIED PHYSICS   97 ( 10 )   104509 - 104509   2005.5

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  • Spectroscopic characterization of single-walled carbon nanotubes carrier-doped by encapsulation of TCNQ

    M Shiraishi, S Swaraj, T Takenobu, Y Iwasa, M Ata, WES Unger

    PHYSICAL REVIEW B   71 ( 12 )   125419   2005.3

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  • Pressure screening in the interior of primary shells in double-wall carbon nanotubes

    J Arvanitidis, D Christofilos, K Papagelis, KS Andrikopoulos, T Takenobu, Y Iwasa, H Kataura, S Ves, GA Kourouklis

    PHYSICAL REVIEW B   71 ( 12 )   125404   2005.3

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  • Large optical nonlinearity of semiconducting single-walled carbon nanotubes under resonant excitations

    A Maeda, S Matsumoto, H Kishida, T Takenobu, Y Iwasa, M Shiraishi, M Ata, H Okamoto

    PHYSICAL REVIEW LETTERS   94 ( 4 )   047404   2005.2

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  • Direct comparison of field-effect and electrochemical doping in regioregular poly(3-hexylthiophene)

    H Shimotani, G Diguet, Y Iwasa

    APPLIED PHYSICS LETTERS   86 ( 2 )   022104   2005.1

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  • Nonlinear and ultrafast optical response in single-walled carbon nanotubes

    A Maeda, S Matsumoto, H Kishida, T Takenobu, Y Iwasa, M Shiraishi, M Ata, H Okamoto

    Second International Conference on Photo-Induced Phase Transitions: Cooperative, Nonlinear and Functional Properties   21   177 - 182   2005

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  • Solution-processed fabrication of single-walled carbon nanotube field effect transistors

    M Shiraishi, T Takenobu, Y Iwasa, T Iwai, H Kataura, M Ata

    FULLERENES NANOTUBES AND CARBON NANOSTRUCTURES   13   485 - 489   2005

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  • Gate-induced crossover from unconventional metals to Fermi liquids in multiwalled carbon nanotubes

    T Kanbara, T Iwasa, K Tsukagoshi, Y Aoyagi, Y Iwasa

    APPLIED PHYSICS LETTERS   85 ( 26 )   6404 - 6406   2004.12

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  • Effects of polarized organosilane self-assembled monolayers on organic single-crystal field-effect transistors

    J. Takeya, T. Nishikawa, T. Takenobu, S. Kobayashi, Y. Iwasa, T. Mitani, C. Goldmann, C. Krellner, B. Batlogg

    Applied Physics Letters   85 ( 21 )   5078 - 5080   2004.11

  • Electronic properties for the C-2v and C-s isomers of Pr@C-82 studied by Raman, resistivity and scanning tunneling micro scopy/spectroscopy

    T Hosokawa, S Fujiki, E Kuwahara, Y Kubozono, H Kitagawa, A Fujiwara, T Takenobu, Y Iwasa

    CHEMICAL PHYSICS LETTERS   395 ( 1-3 )   78 - 81   2004.9

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  • High-pressure study of layered nitride superconductors

    Y Taguchi, M Hisakabe, Y Ohishi, S Yamanaka, Y Iwasa

    PHYSICAL REVIEW B   70 ( 10 )   Art. No. 104506   2004.9

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  • Single-walled carbon nanotube aggregates for solution-processed field effect transistors

    M Shiraishi, T Takenobu, T Iwai, Y Iwasa, H Kataura, M Ata

    CHEMICAL PHYSICS LETTERS   394 ( 1-3 )   110 - 113   2004.8

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  • Structural and electronic characterizations of two isomers of Ce@C-82

    Y Rikiishi, Y Kubozono, T Hosokawa, K Shibata, Y Haruyama, Y Takabayashi, A Fujiwara, S Kobayashi, S Mori, Y Iwasa

    JOURNAL OF PHYSICAL CHEMISTRY B   108 ( 23 )   7580 - 7585   2004.6

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  • A screening of phage displayed peptides for the recognition of fullerene (C60)

    Y Morita, T Ohsugi, Y Iwasa, E Tamiya

    JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC   28 ( 4-6 )   185 - 190   2004.6

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  • Control of carrier density by self-assembled monolayers in organic field-effect transistors

    S Kobayashi, T Nishikawa, T Takenobu, S Mori, T Shimoda, T Mitani, H Shimotani, N Yoshimoto, S Ogawa, Y Iwasa

    NATURE MATERIALS   3 ( 5 )   317 - 322   2004.5

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  • Infrared optical conductivity and the electronic phase diagram in the organic superconductor kappa-(BEDT-TTF)(2)X

    Ito, I, T Sasaki, N Yoneyama, N Kobayashi, N Hanasaki, H Tajima, T Ito, Y Iwasa

    JOURNAL DE PHYSIQUE IV   114   321 - 322   2004.4

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  • Magnetism and transport characteristics of (Ga,Mn)N in steady high fields

    T Miura, Y Yamamoto, S Itaya, K Suga, K Kindo, T Takenobu, Y Iwasa, H Hori

    PHYSICA B-CONDENSED MATTER   346   402 - 407   2004.4

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  • Structural analysis of intercalation compounds of pentacene

    Takayoshi Ito, Tadaoki Mitani, Taishi Takenobu, Yoshihiro Iwasa

    Journal of Physics and Chemistry of Solids   65 ( 2-3 )   609 - 613   2004.2

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  • Structural analysis if intercalation compounds of pentacene

    T Ito, T Mitani, T Takenobu, Y Iwasa

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   65 ( 2-3 )   609 - 613   2004.2

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  • Raman spectroscopic study of carbon substitution in MgB2

    J Arvanitidis, K Papagelis, K Prassides, GA Kourouklis, S Ves, T Takenobu, Y Iwasa

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   65 ( 1 )   73 - 77   2004.1

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  • Quantum chemical study on the configurations of encapsulated metal ions and the molecular vibration modes in endohedral dimetallofullerene La-2@C-80

    H Shimotani, T Ito, Y Iwasa, A Taninaka, H Shinohara, E Nishibori, M Takata, M Sakata

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   126 ( 1 )   364 - 369   2004.1

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  • The spin chirality induced anomalous Hall effect in pyrochlore ferromagnets

    JOURNAL OF PHYSICS-CONDENSED MATTER   16 (11)   S599-S606   2004

  • 急展開を見せる単層カーボンナノチューブの化学

    化学同人 化学   59 ( 4 )   68 - 69   2004

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  • Absorbing Discoveries on the Nanoscale

    Look Japan   49 ( 576 )   24 - 24   2004

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  • Electronic correlation in the infrared optical properties of the quasi-two-dimensional kappa-type BEDT-TTF dimer system

    PHYSICAL REVIEW B   69(6)   Art.No.064508   2004

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  • The spin chirality induced anomalous Hall effect in pyrochlore ferromagnets

    JOURNAL OF PHYSICS-CONDENSED MATTER   16 (11)   S599-S606   2004

  • Absorbing Discoveries on the Nanoscale

    Look Japan   49 ( 576 )   24 - 24   2004

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  • Quantum chemical study on the configurations of encapsulated metal ions and the molecular vibration modes in endohedral dimetallofullerene La-2@C-80

    Journal of the American Chemical Society   126 ( 1 )   364 - 369   2004

  • Electronic correlation in the infrared optical properties of the quasi-two-dimensional kappa-type BEDT-TTF dimer system

    PHYSICAL REVIEW B   69(6)   Art.No.064508   2004

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  • Structural and electronic properties of selected fulleride salts

    S Margadonna, Y Iwasa, T Takenobu, K Prassides

    FULLERENE-BASED MATERIALS: STRUCTURES AND PROPERTIES   109   127 - 164   2004

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    DOI: 10.1007/b94381

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  • Stable and controlled amphoteric doping by encapsulation of organic molecules inside carbon nanotubes

    T Takenobu, T Takano, M Shiraishi, Y Murakami, M Ata, H Kataura, Y Achiba, Y Iwasa

    NATURE MATERIALS   2 ( 10 )   683 - 688   2003.10

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  • Conductivity and field effect transistor of La-2@C-80 metallofullerene

    S Kobayashi, S Mori, S Iida, H Ando, T Takenobu, Y Taguchi, A Fujiwara, A Taninaka, H Shinohara, Y Iwasa

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   125 ( 27 )   8116 - 8117   2003.7

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  • Fabrication and characterization of C60 thin-film transistors with high field-effect mobility

    S. Kobayashi, T. Takenobu, S. Mon, A. Fujiwara, Y. Iwasa

    Applied Physics Letters   82 ( 25 )   4581 - 4583   2003.6

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    DOI: 10.1063/1.1577383

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  • Microwave conductivity of superconducting and insulating fullerides

    H Kitano, R Matsuo, K Miwa, A Maeda, T Takenobu, Y Iwasa

    JOURNAL OF LOW TEMPERATURE PHYSICS   131 ( 5-6 )   1251 - 1258   2003.6

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  • Fabrication and characterization of C-60 thin-film transistors with high field-effect mobility

    S Kobayashi, T Takenobu, S Mori, A Fujiwara, Y Iwasa

    APPLIED PHYSICS LETTERS   82 ( 25 )   4581 - 4583   2003.6

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  • Metal-insulator transition in C-60 fullerides

    Y Iwasa, T Takenobu, H Kitano, A Maeda

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   388   615 - 616   2003.5

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  • Superconductivity, Mott-Hubbard states, and molecular orbital order in intercalated fullerides

    Y. Iwasa, T. Takenobu

    Journal of Physics Condensed Matter   15 ( 13 )   R495 - R519   2003.4

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    DOI: 10.1088/0953-8984/15/13/202

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  • Dielectric and magnetic properties of metallofullerene La@C-82 solids

    Y Iwasa, CJ Nuttall

    SYNTHETIC METALS   135 ( 1-3 )   773 - 774   2003.4

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  • Extraordinarily high reduction states of fullerenes produced by intercalation with divalent metals

    T Ito, T Takenobu, Y Iwasa, T Mitani

    SYNTHETIC METALS   135 ( 1-3 )   789 - 790   2003.4

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  • Hydrogen storage in C-70 encapsulated single-walled carbon nanotube

    T Takenobu, M Shiraishi, A Yamada, M Ata, H Kataura, Y Iwasa

    SYNTHETIC METALS   135 ( 1-3 )   787 - 788   2003.4

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  • mu SR studies of superconducting MgB1.96C0.04

    K Papagelis, J Arvanitidis, Margiolaki, I, K Brigatti, K Prassides, A Schenck, A Lappas, A Amato, Y Iwasa, T Takenobu

    PHYSICA B-CONDENSED MATTER   326 ( 1-4 )   346 - 349   2003.2

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  • Synthesis, structure, and magnetic properties of the fullerene-based ferromagnets Eu3C70 and Eu9C70

    T Takenobu, DH Chi, S Margadonna, K Prassides, Y Kubozono, AN Fitch, K Kato, Y Iwasa

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   125 ( 7 )   1897 - 1904   2003.2

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  • Antiferromagnetic ordering in the expanded (NH3)Rb3C60 fulleride

    J Arvanitidis, K Papagelis, T Takenobu, Margiolaki, I, K Brigatti, K Prassides, Y Iwasa, A Lappas

    PHYSICA B-CONDENSED MATTER   326 ( 1-4 )   572 - 576   2003.2

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  • The effect of anisotropic intermolecular interactions on the pressure response of polymeric fullerenes

    J Arvanitidis, S Assimopoulos, K Papagelis, S Ves, K Prassides, Y Iwasa, GA Kourouklis

    PHYSICA STATUS SOLIDI B-BASIC RESEARCH   235 ( 2 )   369 - 373   2003.2

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  • Photoinduced electron transfer and enhanced fluorescence Of C-60 pearl-necklace polymers

    LX Xiao, H Shimotani, N Dragoe, A Sugita, K Saigo, Y Iwasa, T Kobayashi, K Kitazawa

    CHEMICAL PHYSICS LETTERS   368 ( 5-6 )   738 - 744   2003.1

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  • mu+SR study of carbon-doped MgB2 superconductors

    K Papagelis, J Arvanitidis, K Prassides, A Schenck, T Takenobu, Y Iwasa

    EUROPHYSICS LETTERS   61 ( 2 )   254 - 260   2003.1

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  • Bond switching from two-to theree-dimensional polymers of C-60 at high pressure

    PHYSICAL REVIEW B   68(15)   Art.No.153402   2003

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  • Pressure-induced transformation and phonon modes of the two-dimensional rhombohedral polymer of C-60: A Raman spectroscopic study

    Physical Review B   68   Art. No. 094103   2003

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  • カーボンナノチューブのインターカレーション

    パリティ   18   25 - 25   2003

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  • Bond switching from two-to theree-dimensional polymers of C-60 at high pressure

    PHYSICAL REVIEW B   68(15)   Art.No.153402   2003

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  • Superconductivity, Mott-Hubbard states, and molecular orbital order in intercalated fullerides

    IWASA Y, TAKENOBU T

    Journal of Physics-Condensed Matter   15 ( 13 )   R495 - R519   2003

  • Pressure-induced transformation and phonon modes of the two-dimensional rhombohedral polymer of C-60: A Raman spectroscopic study

    Physical Review B   68   Art. No. 094103   2003

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  • Magnetic field induced sign reversal of the anomalous Hall effect in a pyrochlore ferromagnet Nd2Mo2O7: Evidence for a spin chirality mechanism

    Physical Review Letters   90   Art. No. 257202   2003

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  • Structural and electronic properties of Ce@C-82

    Physical Review B   68   Art. No. 094104   2003

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  • Pressure-induced structural phase transition in fullerides doped with rare-earth metals

    Physical Review B   67   Art. No. 094101   2003

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  • Magnetic field induced sign reversal of the anomalous Hall effect in a pyrochlore ferromagnet Nd2Mo2O7: Evidence for a spin chirality mechanism

    Physical Review Letters   90   Art. No. 257202   2003

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  • Structural and electronic properties of Ce@C-82

    Physical Review B   68   Art. No. 094104   2003

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  • Pressure-induced structural phase transition in fullerides doped with rare-earth metals

    Physical Review B   67   Art. No. 094101   2003

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  • Carbon miscibility in the boron layers of the MgB2 superconductor

    Maurin, I, S Margadonna, K Prassides, T Takenobu, Y Iwasa, AN Fitch

    CHEMISTRY OF MATERIALS   14 ( 9 )   3894 - 3897   2002.9

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  • Phase separation in carbon-doped MgB2 studied by means of alternating current susceptibility measurements

    K Papagelis, J Arvanitidis, S Margadonna, Y Iwasa, T Takenobu, M Pissass, K Prassides

    JOURNAL OF PHYSICS-CONDENSED MATTER   14 ( 31 )   7363 - 7369   2002.8

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  • Metal-insulator transition of donor-acceptor-type organic charge-transfer complex (BETS)(2)(Br(2)TCNQ): Site-selective NMR measurements

    K Hiraki, S Furuta, T Takahashi, R Kondo, S Kagoshima, T Hasegawa, T Mochida, Y Iwasa

    PHYSICAL REVIEW B   66 ( 3 )   035104-1-035104-6   2002.7

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  • Bridging fullerenes with metals

    DH Chi, Y Iwasa, XH Chen, T Takenobu, T Ito, T Mitani, E Nishibori, M Takata, M Sakata, Y Kubozono

    CHEMICAL PHYSICS LETTERS   359 ( 3-4 )   177 - 183   2002.6

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  • Structural stability of the rhombohedral 2D polymeric phase of C-60 studied by in-situ Raman scattering at pressures up to 30 GPa

    KP Meletov, J Arvanitidis, GA Kourouklis, K Prassides, Y Iwasa

    CHEMICAL PHYSICS LETTERS   357 ( 3-4 )   307 - 313   2002.5

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  • 25pXM-2 NMR study on (BETS)_2(X_2TCNQ) (X=Br,Cl) V

    Furuta S., Hiraki K., Takahashi T., Kondo R., Kagoshima S., Hasegawa T., Mochida T., Iwasa Y.

    Meeting abstracts of the Physical Society of Japan   57 ( 1 )   780 - 780   2002.3

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  • 高容量電池

    ケミカルエンジニアリング   47   269 - 269   2002

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  • フラーレン固体における分子回転と物性の相関

    固体物理   37   595 - 595   2002

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  • Handbook of Superconducting Materials Vol.1 Superconductivity, Materials, and Processing

    Institute of Physics Publishing   2002

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  • Observation of the vortex lattice phase transition in the specific heat in La1.86Sr0.14CuO4 single crystal

    Physica C-Superconductivity and Its Applications   366 ( 2 )   129 - 134   2002

  • Evidence for insulating behavior in the electric conduction of (NH3)K3C60 systems

    Physical Review Letters   88   Art. No. 096401   2002

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  • Intercalation processes of single-walled carbon nanotube ropes

    Y Iwasa, H Fudo, Y Yatsu, T Mitani, H Kataura, Y Achiba

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   12 ( 5 )   325 - 330   2002

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  • Dipole dynamics in the endohedral metallofullerene La@C-82

    Advanced Materials   14 ( 4 )   293 - 296   2002

  • Heat capacity and Gruneisen functions of negative thermal expansion compound HfW2O8

    Y Yamamura, N Nakajima, T Tsuji, Y Iwasa, K Saito, M Sorai

    SOLID STATE COMMUNICATIONS   121 ( 4 )   213 - 217   2002

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  • Handbook of Superconducting Materials Vol.1 Superconductivity, Materials, and Processing

    Institute of Physics Publishing   2002

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  • 炭素だけから磁石ができる?

    Levi Barbara Goss, 岩佐 義宏

    パリティ   17 ( 4 )   46 - 48   2002

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  • Observation of the vortex lattice phase transition in the specific heat in La1.86Sr0.14CuO4 single crystal

    IWASAKI H, CHIGIRA T, NAITO T, MORIYAMA S, IWASA Y, NISHIZAKI T, KOBAYASHI N

    Physica C-Superconductivity and Its Applications   366 ( 2 )   129 - 134   2002

  • Evidence for insulating behavior in the electric conduction of (NH3)K3C60 systems

    Physical Review Letters   88   Art. No. 096401   2002

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  • Dipole dynamics in the endohedral metallofullerene La@C-82

    NUTTALL C J, HAYASHI Y, YAMAZAKI K, MITANI T, IWASA Y

    Advanced Materials   14 ( 4 )   293 - 296   2002

  • Superconductivity and metal-insulator transition in twin-columnar organic superconductor, (BETS)(2)(X(2)TCNQ) [X=Cl, Br]

    R Kondo, T Hasegawa, T Mochida, S Kagoshima, Y Iwasa, K Hiraki, T Takahashi

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   70 ( 10 )   3023 - 3030   2001.10

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  • Pressure evolution of the structure of (NH3)K3C60

    S Margadonna, K Prassides, H Simoda, Y Iwasa, M Mezouar

    EUROPHYSICS LETTERS   56 ( 1 )   61 - 66   2001.10

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  • Positron annihilation inside C-60

    Y Ito, Y Iwasa, NM Tuan, S Moriyama

    JOURNAL OF CHEMICAL PHYSICS   115 ( 10 )   4787 - 4790   2001.9

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  • Electrical conduction of (NH3)(x)NaRb2C60

    A Maeda, R Matsuo, H Kitano, R Inoue, T Takenobu, Y Iwasa, T Mitani

    PHYSICA C   357   99 - 102   2001.8

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  • Vibrational spectroscopy of superconducting MgB2 by neutron inelastic scattering

    T Muranaka, S Margadonna, Maurin, I, K Brigatti, D Colognesi, K Prassides, Y Iwasa, M Arai, M Takata, J Akimitsu

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   70 ( 6 )   1480 - 1482   2001.6

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  • Poly(1,4-phenylene-1,2,4-dithiazol-3 ',5 '-yl): the new redox system for lithium secondary batteries

    H Uemachi, Y Iwasa, T Mitani

    ELECTROCHIMICA ACTA   46 ( 15 )   2305 - 2312   2001.4

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  • Mott-Hubbard transition in alkali ammonia fullerides

    T Takenobu, T Muro, Y Iwasa, T Mitani

    SYNTHETIC METALS   121 ( 1-3 )   1173 - 1174   2001.3

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  • Intermolecular interaction of complexes with anti-formed metal octaethylporphyrins and C-60

    T Ishii, N Aizawa, M Yamashita, H Matsuzaka, Ikemoto, I, K Kikuchi, T Kodama, Y Iwasa

    SYNTHETIC METALS   121 ( 1-3 )   1165 - 1166   2001.3

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  • Phase stability of doped carbon nanotubes

    Y Iwasa, H Fudo, Y Yatsu, T Mitani, H Kataura, Y Achiba

    SYNTHETIC METALS   121 ( 1-3 )   1203 - 1204   2001.3

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  • Donor-acceptor-type complexes of (BEDT-TTF)(TCNQ) analogues: Peculiar magnetic transition in (BEDO-TTF)(Cl(2)TCNQ)

    T Hasegawa, R Kondo, S Kagoshima, Y Iwasa, T Mochida, T Akutagawa, T Nakamura

    SYNTHETIC METALS   120 ( 1-3 )   991 - 992   2001.3

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  • Electronic properties of novel donor-acceptor type charge transfer complexes, (BETS)(2)(X(2)TCNQ) (X = Cl, Br): H-1, Se-77 and C-13-NMR

    K Hiraki, T Takahashi, R Kondo, S Kagoshima, T Hasegawa, T Mochida, Y Iwasa

    SYNTHETIC METALS   120 ( 1-3 )   917 - 918   2001.3

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  • Metal-insulator transition in donor-acceptor type superconductor, (BETS)(2)(X(2)TCNQ)

    R Kondo, T Hasegawa, S Kagoshima, T Mochida, Y Iwasa

    SYNTHETIC METALS   120 ( 1-3 )   995 - 996   2001.3

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  • Bistability effects in solvent-including metallofullerene crystals

    CJ Nuttall, Y Inada, K Nagai, Y Hayashi, T Kitani, Y Iwasa

    SYNTHETIC METALS   121 ( 1-3 )   1175 - 1176   2001.3

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  • Electronic states of novel donor/acceptor type of organic superconductor, (BETS)(2)(Cl(2)TCNQ)

    K Hiraki, T Takahashi, R Kondo, S Kagoshima, T Hasegawa, T Mochida, Y Iwasa

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   62 ( 1-2 )   401 - 403   2001.1

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  • Formation mechanism of polymeric fullerenes

    Y Iwasa, T Ozaki, T Mitani

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   355   445 - 456   2001

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  • カーボンナノ構造による物性制御

    日本結晶成長学会誌   28   145 - 151   2001

  • フラーレン超伝導体

    材料科学   38   255 - 255   2001

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  • Intralayer carbon substitution in the MgB2 superconductor

    Phy.Rev.B   64   134513-1-134513-4   2001

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  • Current status of doped C-60 solids: Superconductors and related materials

    Y Iwasa

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   11 ( 6 )   415 - 425   2001

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  • Compressibility of the MgB2 Superconductor

    Phy.Rev.B   64   012509-1-012509-4   2001

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  • Pressure dependence of T-c in the MgB2 superconductor as probed by resistivity measurements

    SAITO E, TAKNENOBU T, ITO T, IWASA Y, PRASSIDES K, ARIMA T

    Journal of Physics-Condensed Matter   13 ( 12 )   L267 - L270   2001

  • Neutral-ionic phase transition of(BEDT-TTF)(CIMeTCNQ) under pressure

    Phys. Rev. B   64   085106-1-085106-4   2001

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  • Orientational ordering of C60 in the antiferromagnetic(NH3)K3C60 phase

    Phys. Rev.B   64   132414-1-132414-4   2001

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  • 単層カーボンナノチューブへのインターカレーションとリチウムイオン電池特性

    岩佐 義宏

    機能材料   21 ( 5 )   45 - 48   2001

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  • Current status of doped C-60 solids: Superconductors and related materials

    New Diamond and Frontier Carbon Technology   11   415 - 425   2001

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  • Compressibility of the MgB2 Superconductor

    Phy.Rev.B   64   012509-1-012509-4   2001

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  • Pressure dependence of T-c in the MgB2 superconductor as probed by resistivity measurements

    Journal of Physics-Condensed Matter   13 ( 12 )   L267 - L270   2001

  • Neutral-ionic phase transition of(BEDT-TTF)(CIMeTCNQ) under pressure

    Phys. Rev. B   64   085106-1-085106-4   2001

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  • Orientational ordering of C60 in the antiferromagnetic(NH3)K3C60 phase

    Phys. Rev.B   64   132414-1-132414-4   2001

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  • Far-infrared investigation of C-60 high-pressure-high-temperature polymers and dimer

    VC Long, JL Musfeldt, K Kamaras, Y Iwasa, WE Mayo

    FERROELECTRICS   249 ( 1-2 )   135 - 144   2001

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  • Intralayer carbon substitution in the MgB2 superconductor

    Phy.Rev.B   64   134513-1-134513-4   2001

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  • Measurement of complex electrical conductivity of metallic powders in a sealed tube

    A Maeda, R Matsuo, R Inoue, H Kitano, T Takenobu, Y Iwasa, T Mitani

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   39 ( 11 )   6459 - 6464   2000.11

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  • Raman behavior of two A(g) modes in the fullerides with t(1g) states

    XH Chen, T Takenobu, Z Sun, Y Iwasa

    PHYSICA C   341 ( Pt.4 )   2263 - 2264   2000.11

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  • Mixed-stack organic charge-transfer complexes with intercolumnar networks

    T. Hasegawa, T. Mochida, R. Kondo, S. Kagoshima, Y. Iwasa, T. Akutagawa, T. Nakamura, G. Saito

    Physical Review B - Condensed Matter and Materials Physics   62 ( 15 )   10059 - 10066   2000.10

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  • Low-temperature bistability in the magnetic properties of solvent-including lanthanide metallofullerene crystals

    C. J. Nuttall, Y. Inada, K. Nagai, Y. Iwasa

    Physical Review B - Condensed Matter and Materials Physics   62 ( 13 )   8592 - 8595   2000.10

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  • Structure and Raman behaviour of Sm2.75C60

    Z Sun, XH Chen, T Takenobu, Y Iwasa

    JOURNAL OF PHYSICS-CONDENSED MATTER   12 ( 41 )   8919 - 8926   2000.10

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  • Investigation of epitaxial arrangement and electronic structure of a La@C82 film grown on an MoS2 surface

    K. Iizumi, Y. Uchino, K. Ueno, A. Koma, K. Saiki, Y. Inada, K. Nagai, Y. Iwasa, T. Mitani

    Physical Review B - Condensed Matter and Materials Physics   62 ( 12 )   8281 - 8285   2000.9

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  • Structure and Raman scattering of Cs3C60 under high pressure

    S. Fujiki, Y. Kubozono, S. Emura, Y. Takabayashi, S. Kashino, A. Fujiwara, K. Ishii, H. Suematsu, Y. Murakami, Y. Iwasa, T. Mitani, H. Ogata

    Physical Review B - Condensed Matter and Materials Physics   62 ( 9 )   5366 - 5369   2000.9

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  • Antiferromagnetism and phase diagram in ammoniated alkali fulleride salts

    T Takenobu, T Muro, Y Iwasa, T Mitani

    PHYSICAL REVIEW LETTERS   85 ( 2 )   381 - 384   2000.7

  • Mott transition with antiferromagnetic ordering in ammoniated alkali C-60 superconductors: NMR studies

    H Tou, N Muroga, Y Maniwa, H Shimoda, Y Iwasa, T Mitani

    PHYSICA B-CONDENSED MATTER   281   1018 - 1020   2000.6

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  • Synthesis, structure, and transport properties of novel fullerides A(3)C(70) (A = Ba and Sm)

    XH Chen, DH Chi, Z Sun, T Takenobu, ZS Liu, Y Iwasa

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   122 ( 24 )   5729 - 5732   2000.6

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  • Stiffness of single-walled carbon nanotubes under large strain

    T Ozaki, Y Iwasa, T Mitani

    PHYSICAL REVIEW LETTERS   84 ( 8 )   1712 - 1715   2000.2

  • Anomalous high pressure properties in fullerene superconductors

    Taishi Taken Obu, Hideo Shimoda, Yoshihiro Iwasa, Tadaoki Mitani, Mayumi Kosaka, Kats Umitanigaki, Craig M. Brown, Kosmas Prassides

    Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals   340   599 - 604   2000

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    Language:English   Publisher:Gordon & Breach Science Publ Inc  

    DOI: 10.1080/10587250008025532

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  • Far-infrared vibrational properties of high-pressure high- temperature C-60 polymers and the C-60 dimer

    Physical Review B   61 ( 19 )   13191 - 13201   2000

  • First syntheses of cocrystallites consisting of anti-formed metal octaethylporphyrins with fullerene C-60

    T Ishii, N Aizawa, M Yamashita, H Matsuzaka, T Kodama, K Kikuchi, Ikemoto, I, Y Iwasa

    JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS   ,4407-4412 ( 23 )   4407 - 4412   2000

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  • Electronic properties of Ba-intercalated fullerides

    Y Iwasa, XH Chen, T Takenobu, T Mitani

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   340   583 - 586   2000

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  • Pressure dependence of magnetization of M[N(CN)2]2: Mechanism for the long range magnetic ordering

    Mol.Cryst.Liq.Cryst   343   227 - 234   2000

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  • Synthesis and structure of BaxC70

    Taishi Takenobu, Xianhui Chen, Yoshihiro Iwasa, Tadaoki Mitani

    Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals   340   617 - 622   2000

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    DOI: 10.1080/10587250008025535

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  • Magnetic properties of metal endohedral fullerene crystals La@C-82 center dot(Cs-2)(1.5)

    CJ Nuttall, Y Inada, K Nagai, Y Hayashi, T Kitani, Y Iwasa

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   343   553 - 558   2000

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  • フラーレン系のモット転移と軌道縮退の効果

    岩佐 義宏

    固体物理   35 ( 10 )   799 - 805   2000

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  • Preparation and charge-discharge properties of a novel organosulfur polymer, poly(p-phenylene thiuret), for battery applications

    Chemistry Letters   ,946-947   2000

  • NMR evidence for Mott-Hubbard localization in (NH3)K3C60

    TOU H, MANIWA Y, IWASA Y, SHIMODA H, MITANI T

    Physical Review B   62 ( 2 )   R775 - R778   2000

  • Magnetic resonance in the antiferromagnetic and normal state of NH3K3C60

    SIMON F, JANOSSY A, MURANYI F, FEHER T, SHIMODA H, IWASA Y, FORRO L

    Physical Review B   61 ( 6 )   R3826 - R3829   2000

  • Far-infrared vibrational properties of high-pressure high- temperature C-60 polymers and the C-60 dimer

    LONG V C, MUSFELDT J L, KAMARAS K, ADAMS G B, PAGE J B, IWASA Y, MAYO W E

    Physical Review B   61 ( 19 )   13191 - 13201   2000

  • Pressure dependence of magnetization of M[N(CN)2]2: Mechanism for the long range magnetic ordering

    Mol.Cryst.Liq.Cryst   343   227 - 234   2000

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  • Synthesis and structure of BaxC70

    T Takenobu, XH Chen, Y Iwasa, T Mitani

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   340   617 - 622   2000

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  • Structural phase transition in (NH3)K3C60

    K. Ishii, T. Watanuki, A. Fujiwara, H. Suematsu, Y. Iwasa, H. Shimoda, T. Takenobu, T. Mitani

    Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals   340   571 - 576   2000

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    DOI: 10.1080/10587250008025527

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  • Preparation and charge-discharge properties of a novel organosulfur polymer, poly(p-phenylene thiuret), for battery applications

    Chemistry Letters   ,946-947   2000

  • NMR evidence for Mott-Hubbard localization in (NH3)K3C60

    Physical Review B   62 ( 2 )   R775 - R778   2000

  • Structural and magnetic characterisation of Ce@C-82

    CJ Nuttall, Y Inada, Y Watanabe, K Nagai, T Muro, DH Chi, T Takenobu, Y Iwasa, K Kikuchi

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   340   635 - 638   2000

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  • Magnetic resonance in the antiferromagnetic and normal state of NH3K3C60

    Physical Review B   61 ( 6 )   R3826 - R3829   2000

  • Magnetic ordering in the ammoniated fulleride (ND3)K3C60

    K Prassides, S Margadonna, D Arcon, A Lappas, H Shimoda, Y Iwasa

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   121 ( 48 )   11227 - 11228   1999.12

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  • Rotational tunneling of ammonia in (NH3)K3C60

    S Margadonna, K Prassides, CM Brown, H Shimoda, Y Iwasa, H Casalta

    JOURNAL OF CHEMICAL PHYSICS   111 ( 24 )   10969 - 10973   1999.12

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  • Temperature dependence of Raman scattering in K3Ba3C60

    XH Chen, YM Xiong, Z Sun, T Takenobu, H Kitagawa, Y Iwasa

    JOURNAL OF PHYSICS-CONDENSED MATTER   11 ( 42 )   8329 - 8340   1999.10

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  • 25pF-3 Infrared Absorption of Single walled Carbon Nanotube

    Fudo H, Fukawa M, Ahn J, Iwasa Y, MItani Y, Kataura H, Acbiba Y

    Meeting abstracts of the Physical Society of Japan   54 ( 2 )   750 - 750   1999.9

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  • Structure and properties of a fullerideSm6C60

    X. H. Chen, Z. S. Liu, S. Y. Li, D. H. Chi, Y. Iwasa

    Physical Review B   60 ( 9 )   6183 - 6186   1999.9

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  • Structural and electronic properties of the noncubic superconducting fullerides A ' C-4(60) (A '= Ba, Sr)

    CM Brown, S Taga, B Gogia, K Kordatos, S Margadonna, K Prassides, Y Iwasa, K Tanigaki, AN Fitch, P Pattison

    PHYSICAL REVIEW LETTERS   83 ( 11 )   2258 - 2261   1999.9

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  • Band filling and width control in fullerides

    Y Iwasa, S Taga, T Takenobu, H Shimoda, T Mitani, K Prassides, CM Brown

    SYNTHETIC METALS   103 ( 1-3 )   2462 - 2465   1999.6

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  • Anomalous high pressure effect in superconducting fullerides

    T Takenobu, H Shimoda, Y Iwasa, T Mitani, C Murayama, N Mori, K Ishii, H Suematsu

    SYNTHETIC METALS   103 ( 1-3 )   2445 - 2446   1999.6

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  • Structure and properties of (BEDSe-TTF)(Fn-TCNQ) charge transfer complexes (n=1, 2, 4)

    T Mochida, H Moriyama, T Hasegawa, R Kondo, S Kagoshima, Y Iwasa

    SYNTHETIC METALS   102 ( 1-3 )   1678 - 1679   1999.6

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  • NMR studies of ammoniated NaA(2)C(60) superconductors

    Y Maniwa, N Muroga, H Tou, K Kikuchi, S Suzuki, Y Achiba, M Kosaka, K Tanigaki, Y Iwasa, H Shimoda, T Mitani

    SYNTHETIC METALS   103 ( 1-3 )   2458 - 2461   1999.6

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  • C-13-NMR studies of t(1g)-derived fullerene superconductors

    H Tou, Y Maniwa, S Taga, Y Iwasa, T Mitani, K Tanigaki, B Gogia, H Suematsu

    SYNTHETIC METALS   102 ( 1-3 )   1563 - 1564   1999.6

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  • Structure and properties of ail organic conductor (BEDT-TseF)(2)(X(1)X(2)TCNQ) (X-1,X-2=Cl,Br)

    R Kondo, S Kagoshima, T Hasegawa, T Mochida, Y Iwasa

    SYNTHETIC METALS   102 ( 1-3 )   1628 - 1629   1999.6

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  • Electronic phase transition of BEDT-TTF based mixed-stack charge-transfer complexes

    T Hasegawa, T Akutagawa, T Nakamura, Y Sasou, R Kondo, S Kagoshima, T Mochida, G Saito, Y Iwasa

    SYNTHETIC METALS   103 ( 1-3 )   1804 - 1805   1999.6

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  • Antiferromagnetic ordering in (NH3)K3C60 - C-13-NMR studies

    H Tou, Y Maniwa, H Shimoda, Y Iwasa, T Mitani

    SYNTHETIC METALS   103 ( 1-3 )   2447 - 2447   1999.6

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  • Organic metals involving double chain donor arrangements, (BMDT-TTF)(2)((RR2)-R-1-TCNQ) [R-1 = H, Me, R-2 = Cl, Br]

    Synthetic Metals   102   1680 - 1681   1999

  • Structural phase transition in the ammoniated alkali C-60 compound (NH3)K3C60

    Ishii Kenji, Watanuki Tetsu, Fujiwara Akihiko, Suematsu Hiroyoshi, Iwasa Yoshihiro, Shimoda Hideo, Mitani Tadaoki, Nakao Hironori, Fujii Yasuhiko, Murakami Youichi, Kawada Hajime

    Physical Review B   59 ( 6 )   3956 - 3960   1999

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    DOI: 10.1103/PhysRevB.59.3956

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  • Pressure dependence of superconductivity in the Na2Rb0.5Cs0.5C60 fulleride

    Physical Review B   59 ( 6 )   4439 - 4444   1999

  • Current issues of intercalation and superconductivity in solid state fullerenes

    Y Iwasa, H Shimoda, T Takenobu, S Honjo, T Mitani, H Tou, Y Maniwa, CM Brown, K Prassides

    FULLERENE SCIENCE AND TECHNOLOGY   7 ( 4 )   587 - 598   1999

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  • Mott transition and antiferromagnetic ordering in intercalated- C-60 superconductor

    Physica B   259/261   868 - 869   1999

  • Rotational dynamics of C-60 in (ND3)K3C60

    Physical Review B   59 ( 2 )   943 - 947   1999

  • Donor-acceptor type superconductor, (BETS)(2)(Cl(2)TCNQ)

    Chemistry Letters   ,333-334   1999

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  • Organic metals involving double chain donor arrangements, (BMDT-TTF)(2)((RR2)-R-1-TCNQ) [R-1 = H, Me, R-2 = Cl, Br]

    Synthetic Metals   102   1680 - 1681   1999

  • Physics and Chemistry of Fullerene Superconductors

    Iwasa Yoshihiro

    54 ( 4 )   274 - 278   1999

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    DOI: 10.11316/butsuri1946.54.274

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  • Raman-scattering study of Ba-doped C-60 with t(1g) states

    CHEN X H, TAGA S, IWASA Y

    Physical Review B   60 ( 6 )   4351 - 4356   1999

  • Structural phase transition in the ammoniated alkali C_<60> compound (NH_3)K_3C_<60>

    Ishii Kenji, Watanuki Tetsu, Fujiwara Akihiko, Suematsu Hiroyoshi, Iwasa Yoshihiro, Shimoda Hideo, Mitani Tadaoki, Nakao Hironori, Fujii Yasuhiko, Murakami Youichi, Kawada Hajime

    Physical Review B   59 ( 6 )   3956 - 3960   1999

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    DOI: 10.1103/PhysRevB.59.3956

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  • Raman-scattering study of Ba-doped C-60 with t(1g) states

    Physical Review B   60 ( 6 )   4351 - 4356   1999

  • Metal-insulator transition at 50K in Na2C60

    Kubozono Y., Takabayashi Y., Fujiki S., Kashino S., Kambe T., Iwasa Y., Emura S.

    Phys.Rev B   59 ( 23 )   15062 - 15069   1999

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    DOI: 10.1103/PhysRevB.59.15062

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  • Anomalous Raman shift in the ternary fullerides with t(1g) states

    Physical Review B   60 ( 17 )   12462 - 12466   1999

  • Metal-insulator transition at 50 K in Na2C60

    Kubozono Y., Takabayashi Y., Fujiki S., Kashino S., Kambe T., Iwasa Y., Emura S.

    Physical Review B   59 ( 23 )   15062 - 15069   1999

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    DOI: 10.1103/PhysRevB.59.15062

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  • Anomalous Raman shift in the ternary fullerides with t(1g) states

    CHEN X H, TAKENOBU T, MURO T, FUDO H, IWASA Y

    Physical Review B   60 ( 17 )   12462 - 12466   1999

  • Pressure dependence of superconductivity in the Na2Rb0.5Cs0.5C60 fulleride

    BROWN C M, TAKENOBU T, KORDATOS K, PRASSIDES K, IWASA Y, TANIGAKI K

    Physical Review B   59 ( 6 )   4439 - 4444   1999

  • Mott transition and antiferromagnetic ordering in intercalated- C-60 superconductor

    TOU H, MANIWA Y, SHIMODA H, IWASA Y, MITANI T

    Physica B   259/261   868 - 869   1999

  • Rotational dynamics of C-60 in (ND3)K3C60

    MARGADONNA S, PRASSIDES K, NEUMANN D A, SHIMODA H, IWASA Y

    Physical Review B   59 ( 2 )   943 - 947   1999

  • Donor-acceptor type superconductor, (BETS)(2)(Cl(2)TCNQ)

    Chemistry Letters   ,333-334   1999

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  • Raman study of Cs3C60 under ambient pressure

    Y Kubozono, S Fujiki, K Hiraoka, T Urakawa, Y Takabayashi, S Kashino, Y Iwasa, H Kitagawa, Y Mitani

    CHEMICAL PHYSICS LETTERS   298 ( 4-6 )   335 - 340   1998.12

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  • Preparation of NaC60 and its physical properties revealed by differential scanning calorimetry, Na-23-NMR and ESR

    Y Takabayashi, Y Kubozono, S Kashino, Y Iwasa, S Taga, T Mitani, H Ishida, K Yamada

    CHEMICAL PHYSICS LETTERS   289 ( 1-2 )   193 - 199   1998.6

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  • Elementary processes in pressure-induced polymerization of C-60

    T Ozaki, Y Iwasa, T Mitani

    CHEMICAL PHYSICS LETTERS   285 ( 5-6 )   289 - 293   1998.3

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  • Photoluminescence of confined excitons in nanoscale C-60 clusters

    JS Ahn, K Suzuki, Y Iwasa, N Otsuka, T Mitani

    JOURNAL OF LUMINESCENCE   76-7   201 - 205   1998.2

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  • Conversion of excitons to spin-soliton pairs in quasi-one-dimensional halogen-bridged metal complexes

    H Okamoto, Y Kaga, Y Shimada, Y Oka, Y Iwasa, T Mitani, M Yamashita

    PHYSICAL REVIEW LETTERS   80 ( 4 )   861 - 864   1998.1

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  • Superconducting and normal-state properties of nonavalent fullerides

    IWASA Y, KAWAGUCHI M, IWASAKI H, MITANI T, WADA N, HASEGAWA T

    Physical Review B   57 ( 21 )   13395 - 13398   1998

  • C-13 NMR and static magnetic susceptibility in C-60 superconductors: Possible influence of Kondo impurity

    MANIWA Y, MUROGA N, SATO N, TOU H, SHIMODA H, KIKUCHI K, KOSAKA M, CHEN X, LABES M M

    Physical Review B   58 ( 17 )   11603 - 11606   1998

  • Superconductivity in alkaline earth fullerides

    ISRF Scientific Highlights   ,34-35   1998

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  • High yield selective synthesis of C-60 dimers

    Chemical Communications   ,1411-1412   1998

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  • Energetics of polymerized fullerites

    Physical Review B   58 ( 24 )   16374 - 16377   1998

  • Superconducting and normal-state properties of nonavalent fullerides

    Physical Review B   57 ( 21 )   13395 - 13398   1998

  • フラーレンが作る新しい固体の世界

    岩佐 義宏

    Isotope News   528   2 - 6   1998

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  • Superconductivity in alkaline earth fullerides

    ISRF Scientific Highlights   ,34-35   1998

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  • High yield selective synthesis of C-60 dimers

    Chemical Communications   ,1411-1412   1998

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  • Energetics of polymerized fullerites

    IWASA Y, TANOUE K, MITANI T, YAGI T

    Physical Review B   58 ( 24 )   16374 - 16377   1998

  • Superconductivity of Fullerides with Tunable Crystal Structure and Band Filling

    Y. Iwasa, H. Shimoda, T. Takenobu, T. Mitani, Y. Maniwa, Y. Murakami, K. Ishii, H. Suematsu

    Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu   7   394 - 398   1998

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  • C-13 NMR and static magnetic susceptibility in C-60 superconductors: Possible influence of Kondo impurity

    Physical Review B   58 ( 17 )   11603 - 11606   1998

  • Structure and superconductivity in alkali-ammonia complex fullerides

    Y Iwasa, H Shimoda, Y Miyamoto, T Mitani, Y Maniwa, O Zhou, TTM Palstra

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   58 ( 11 )   1697 - 1705   1997.11

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  • Current issues in fulleride superconductivity

    K Prassides, K Tanigaki, Y Iwasa

    PHYSICA C   282 ( Pt.1 )   307 - 310   1997.8

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  • XAFS study of bcc fullerene compounds, Rb6C60, Ba6C60 and K3Ba3C60

    Y Kubozono, T Nakai, T Urakawa, Y Yoshida, H Maeda, T Ishii, S Kashino, Y Iwasa, M Kawaguchi, T Mitani, S Emura

    PHYSICA C   288 ( 1-2 )   21 - 27   1997.8

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  • Electronic states and anti-ferromagnetic order in mixed-stack charge-transfer compound (BEDT-TTF)(F(2)TCNQ)

    T Hasegawa, S Kagoshima, T Mochida, S Sugiura, Y Iwasa

    SOLID STATE COMMUNICATIONS   103 ( 8 )   489 - 493   1997.8

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  • Photoluminescence of C-60 aggregates in solution

    JS Ahn, K Suzuki, Y Iwasa, T Mitani

    JOURNAL OF LUMINESCENCE   72-4   464 - 466   1997.6

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  • Infrared spectra of one- and two-dimensional fullerene polymer structures: RbC60 and rhombohedral C-60

    K Kamaras, Y Iwasa, L Forro

    PHYSICAL REVIEW B   55 ( 17 )   10999 - 11002   1997.5

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  • Structural and spectroscopic properties of pressure-induced C-70 polymers

    Y Iwasa, T Furudate, T Fukawa, T Ozaki, T Mitani, T Yagi, T Arima

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   64 ( 3 )   251 - 256   1997.3

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  • Synthesis and superconductivity of (NH3)(x)K3C60

    H Shimoda, Y Iwasa, T Mitani

    SYNTHETIC METALS   85 ( 1-3 )   1593 - 1594   1997.2

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  • Synthesis, structure, and electronic properties of (BEDT-TTF)(R(1)R(2)TCNQ); (R-1=R-2=H, F, Cl, Br, CH3)

    T Mochida, T Hasegawa, S Kagoshima, S Sugiura, Y Iwasa

    SYNTHETIC METALS   86 ( 1-3 )   1797 - 1798   1997.2

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  • Synthesis, structure, and electronic properties of (BEDT-TTF)(F(n)TCNQ) (n=0,1,2,4)

    T Hasegawa, K Inukai, S Kagoshima, T Sugawara, T Mochida, S Sugiura, Y Iwasa

    SYNTHETIC METALS   86 ( 1-3 )   1801 - 1802   1997.2

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  • Superconductivity in potassium intercalated Ba3C60

    Y Iwasa, H Hayashi, T Furudate, M Kawaguchi, T Mitani

    SYNTHETIC METALS   86 ( 1-3 )   2309 - 2310   1997.2

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  • アルカリ・アンモニア・C60超伝導体の開発

    New Superconducting Materials Forum News   60   4 - 9   1997

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  • Electronic properties of fullerenes

    K Morii, C Fujikawa, H Kitagawa, Y Iwasa, T Mitani, T Suzuki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS SCIENCE AND TECHNOLOGY SECTION A-MOLECULAR CRYSTALS AND LIQUID CRYSTALS   296   357 - 364   1997

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  • 超伝導体としてのフラーレン

    (株)クバプロ 高温超伝導体とフラーレンの科学・理解はここまで進んだ   ,146-156   1997

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  • フラーレンの固体物理化学

    電気学会技術報告   623   12 - 15   1997

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  • (Bedt-Ttf)(F(1)Tcnq) and (Bedt-Ttf) (F(2)Tcnq)(X)(Tcnq)(1-X) (X Ca 0.5): All-Organic Metals Down to 2 K

    Chemical Communications   ,1377-1378   1997

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  • (Bedt-Ttf)(F(1)Tcnq) and (Bedt-Ttf) (F(2)Tcnq)(X)(Tcnq)(1-X) (X Ca 0.5): All-Organic Metals Down to 2 K

    Chemical Communications   ,1377-1378   1997

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  • Current issues in fulleride superconductivity

    K. Prassides, K. Tanigaki, Y. Iwasa

    Physica C: Superconductivity and its Applications   282-287 ( 1 )   307 - 310   1997

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    DOI: 10.1016/S0921-4534(97)00271-2

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  • Superconductivity in K3Ba3C60

    Y Iwasa, H Hayashi, T Furudate, T Mitani

    PHYSICAL REVIEW B   54 ( 21 )   14960 - 14962   1996.12

  • Nature of one-dimensional excitons in polysilanes

    T Hasegawa, Y Iwasa, T Koda, H Kishida, Y Tokura, S Wada, H Tashiro, H Tachibana, M Matsumoto

    PHYSICAL REVIEW B   54 ( 16 )   11365 - 11374   1996.10

  • Metal-insulator transition in ammoniated K3C60

    IWASA Y, SHIMODA H, PALSTRA T T M, MANIWA Y, ZHOU O, MITANI T

    Physical Review B   53 ( 14 )   R8836 - R8839   1996

  • Superconductivity in fcc fullerides containing off-centered octahedral cations

    SHIMODA H, IWASA Y, MIYAMOTO Y, MANIWA Y, MITANI T

    Physical Review B   54 ( 22 )   R15653 - R15656   1996

  • Determination of C-13 NMR isotropic Knight shift and deviation from BCS relation in A(3)C(60) superconductors

    MANIWA Y, SUGIURA D, KUME K, KIKUCHI K, ACHIBA Y, HIROSAWA I, TANIGAKI K, SHIMODA H, IWASA Y

    Physical Review B   54 ( 10 )   R6861 - R6864   1996

  • Synthesis, crystal structure and physical properties of charge transfer coordination complex, [Pt(H(2)DAG)(HDAG)][Ni(DMIT)(2)]center dot 1/2H(2)O center dot CH3CN center dot CH3OH

    YAMASHITA M, ICHIKAWA A, HAMA T, OHISHI T, MANABE T, MIYAMAE H, YOSHIDA D, SUGIURA S, MITANI T

    Mol.Cryst.Liq.Cryst   284   391 - 398   1996

  • Metal-insulator transition in ammoniated K3C60

    Physical Review B   53 ( 14 )   R8836 - R8839   1996

  • Superconductivity in fcc fullerides containing off-centered octahedral cations

    Physical Review B   54 ( 22 )   R15653 - R15656   1996

  • Superconductivity in alkali-ammonia complex fullerides

    H Shimoda, Y Iwasa, Y Miyamoto, Y Maniwa, T Mitani

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS SCIENCE AND TECHNOLOGY SECTION A-MOLECULAR CRYSTALS AND LIQUID CRYSTALS   285   181 - 186   1996

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  • Determination of C-13 NMR isotropic Knight shift and deviation from BCS relation in A(3)C(60) superconductors

    Physical Review B   54 ( 10 )   R6861 - R6864   1996

  • Synthesis, crystal structure and physical properties of charge transfer coordination complex, [Pt(H(2)DAG)(HDAG)][Ni(DMIT)(2)]center dot 1/2H(2)O center dot CH3CN center dot CH3OH

    Mol.Cryst.Liq.Cryst   284   391 - 398   1996

  • フラーレンポリマー

    固体物理   31   909 - 916   1996

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  • STRUCTURAL AND ELECTRONIC-PROPERTIES OF (NH3)(X)K3C60

    O ZHOU, TTM PALSTRA, Y IWASA, RM FLEMING, AF HEBARD, PE SULEWSKI, DW MURPHY, BR ZEGARSKI

    PHYSICAL REVIEW B   52 ( 1 )   483 - 489   1995.7

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  • NONLINEAR-OPTICAL SPECTROSCOPY ON POLYSILANES - DEPENDENCE OF EXCITON-STATES ON POLYMER BACKBONE CONFORMATIONS

    T HASEGAWA, Y IWASA, T KODA, H KISHIDA, Y TOKURA, S WADA, H TASHIRO, H TACHIBANA, M MATSUMOTO, RD MILLER

    SYNTHETIC METALS   71 ( 1-3 )   1679 - 1680   1995.4

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  • H-1-NMR STUDY IN 2-DIMENSIONAL MOTT-HUBBARD SYSTEM, (BEDT-TTF) (TCNQ)

    K ISHIDA, Y NIINO, Y KITAOKA, K ASAYAMA, Y IWASA, Y TOKURA

    SYNTHETIC METALS   70 ( 1-3 )   881 - 882   1995.3

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  • PRESSURE-INDUCED CROSS-LINKING OF C-60

    Y IWASA, T ARIMA, LJ ROTHBERG, RM FLEMING, O ZHOU, KB LYONS, SW CHEONG, RC HADDON, AF HEBARD, GA THOMAS

    SYNTHETIC METALS   70 ( 1-3 )   1407 - 1408   1995.3

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  • PSEUDO-GAP AND EFFECTIVE-MASS ENHANCEMENT IN ALKALI-METAL DOPED C-60

    Y IWASA, T KANEYASU, M NAGATA, N MIZUTANI

    SYNTHETIC METALS   70 ( 1-3 )   1361 - 1362   1995.3

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  • SUPERCONDUCTIVITY AT 40K IN CESIUM DOPED C-60

    TTM PALSTRA, O ZHOU, Y IWASA, PE SULEWSKI, RM FLEMING, BR ZEGARSKI

    SOLID STATE COMMUNICATIONS   93 ( 4 )   327 - 330   1995.1

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  • Optical study of electronic structures and phonons in alkali-metal-doped C60

    Y. Iwasa, T. Kaneyasu

    Physical Review B   51 ( 6 )   3678 - 3685   1995

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  • C60ポリマー

    季刊フラーレン   3 ( 2 )   96 - 106   1995

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  • 高圧によるC60ポリマーの生成

    岩佐義宏, 有馬孝尚

    高圧力の科学と技術   4 ( 3 )   231 - 237   1995

  • C60アルカリ金属化合物の物性

    固体物理   30   255 - 268   1995

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  • Optical Study of Electronic Structures and Phonon in Alkali-Metal-Doped C60

    IWASA Y, KANEYASU T

    Phys. Rev   51 ( 6 )   3678 - 3685   1995

  • NEW PHASES OF C-60 SYNTHESIZED AT HIGH-PRESSURE

    Y IWASA, T ARIMA, RM FLEMING, T SIEGRIST, O ZHOU, RC HADDON, LJ ROTHBERG, KB LYONS, HL CARTER, AF HEBARD, R TYCKO, G DABBAGH, JJ KRAJEWSKI, GA THOMAS, T YAGI

    SCIENCE   264 ( 5165 )   1570 - 1572   1994.6

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  • Electric-field-induced second-harmonic generation mediated by one-dimensional excitons in polysilanes

    H. Kishida, T. Hasegawa, Y. Iwasa, T. Koda, Y. Tokura, H. Tachibana, M. Matsumoto, S. Wada, T. T. Lay, H. Tashiro

    Physical Review B   50 ( 11 )   7786 - 7792   1994

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  • Charge Transfer at Al-C60 interfaces in thin-film multilayer structures

    Phys. Rev   50 ( 23 )   17740 - 17743   1994

  • 有機錯体結晶の気相成長

    固体物理   29   801 - 804   1994

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  • 分子システムにおける電流スイッチ

    材料科学   30   179 - 185   1994

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  • サッカーボールが重合した

    パリティー   9 ( 11 )   45 - 47   1994

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  • Nonlinear optical study of polysilanes.(invited paper)

    J. Phys. Soc. Jpn.   63   64 - 81   1994

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  • Metal-Insulator Transition and Antiferromagnetic Order in(BEDT-TTF)(TCNQ)

    IWASA Y, MIZUHASHI K, KODA T, TOKURA Y, SAITO G

    Phys. Rev.B   49 ( 5 )   3580 - 3583   1994

  • Charge Transfer at Al-C60 interfaces in thin-film multilayer structures

    HEBARD A F, EOM C B, IWASA Y, LYONS K B, THOMAS G A, RAPKINE D H, FLEMING R M, HADDON R C, EICK R H

    Phys. Rev   50 ( 23 )   17740 - 17743   1994

  • Electronic structures and Jahn-Teller effects in alkali metal fullerides

    Trans.Mat.Res.Soc.Jpn   14B   1085 - 1090   1994

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  • Nonlinear optical study of polysilanes.(invited paper)

    J. Phys. Soc. Jpn.   63   64 - 81   1994

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  • Metal-Insulator Transition and Antiferromagnetic Order in(BEDT-TTF)(TCNQ)

    Phys. Rev.B   49 ( 5 )   3580 - 3583   1994

  • Electronic structures and Jahn-Teller effects in alkali metal fullerides

    Trans.Mat.Res.Soc.Jpn   14B   1085 - 1090   1994

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  • DISPERSION-RELATION IN THE 3RD-ORDER ELECTRIC SUSCEPTIBILITY FOR POLYSILANE FILM

    H KISHIDA, T HASEGAWA, Y IWASA, T KODA, Y TOKURA

    PHYSICAL REVIEW LETTERS   70 ( 24 )   3724 - 3727   1993.6

  • OPTICAL-PROPERTIES OF C-60 AND K3C60

    Y IWASA, T KODA, S KODA

    SYNTHETIC METALS   56 ( 2-3 )   3033 - 3037   1993.4

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  • Dispersion relation in the third-order electric susceptibility for polysilane film

    Phys. Rev. Lett   70 ( 24 )   3724 - 3727   1993

  • Change of electronic structures with varying molecular valence in AxC60

    IWASA Y, WATANABE S, KANEYASU T, YASUDA T, KODA T, NAGATA M, MIZUTANI N

    J. Phys. Chem   54 ( 12 )   1795 - 1800   1993

  • Two-step neutral-ionic transition in organic charge-transfer compounds : Possible staging effect

    IWASA Y, WATANABE N, KODA T, SAITO G

    Phys. Rev   47 ( 5 )   2920 - 2923   1993

  • Dispersion relation in the third-order electric susceptibility for polysilane film

    KISHIDA H, HASEGAWA T, IWASA Y, KODA T, TOKURA Y

    Phys. Rev. Lett   70 ( 24 )   3724 - 3727   1993

  • Change of electronic structures with varying molecular valence in AxC60

    J. Phys. Chem   54 ( 12 )   1795 - 1800   1993

  • Two-step neutral-ionic transition in organic charge-transfer compounds : Possible staging effect

    Phys. Rev   47 ( 5 )   2920 - 2923   1993

  • RESONANCE ENHANCEMENT EFFECT IN NONLINEAR OPTICAL SUSCEPTIBILITY OF POLYSILANES

    Y IWASA, T HASEGAWA, T KODA, Y TOKURA, H TACHIBANA, Y KAWABATA

    SYNTHETIC METALS   50 ( 1-3 )   415 - 421   1992.8

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  • Nonlinear optical spectroscopy on one-dimensional excitons in silicon polymer, polysilane

    Phys. Rev. Lett   69 ( 4 )   668 - 671   1992

  • Chi(3) of M-X Chains

    Molecular Crystals and Liquid Crystals   216   305 - 310   1992

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  • Nonlinear optical spectroscopy on one-dimensional excitons in silicon polymer, polysilane

    HASEGAWA T, IWASA Y, SUNAMURA H, KODA T, TOKURA Y, TACHIBANA H, MATSUMOTO M, ABE S

    Phys. Rev. Lett   69 ( 4 )   668 - 671   1992

  • Two-photon resonant third-hamonic generation in polysilanes

    HASEGAWA T, IWASA Y, KISHIDA H, KODA T, TOKURA Y, TACHIBANA H, KAWABATA Y

    Phys. Rev   45 ( 11 )   6317 - 6320   1992

  • Nonlinear Optical-Properties of Polysilanes

    Molecular Crystals and Liquid Crystals   216   293 - 298   1992

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  • Metallic reflection spectra of K3C60

    IWASA Y, TANAKA K, YASUDA T, KODA T, KODA S

    Phys. Rev. Lett   69 ( 15 )   2284 - 2287   1992

  • Chi(3) of M-X Chains

    Molecular Crystals and Liquid Crystals   216   305 - 310   1992

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  • 白金錯体の非線形光学特性

    シーエムシー出版 新・非線形光学材料   ,159-165   1992

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  • Metallic reflection spectra of K3C60

    Phys. Rev. Lett   69 ( 15 )   2284 - 2287   1992

  • 有機電荷移動錯体における中性-イオン性転移

    岩佐 義宏

    物性研究   58 ( 5 )   445 - 467   1992

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  • Two-photon resonant third-hamonic generation in polysilanes

    Phys. Rev   45 ( 11 )   6317 - 6320   1992

  • Nonlinear Optical-Properties of Polysilanes

    Molecular Crystals and Liquid Crystals   216   293 - 298   1992

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  • SPECTROSCOPIC STUDY ON (ANTI)FERROELECTRIC MOLECULAR-SYSTEMS

    Y IWASA, T KODA, S KOSHIHARA, Y TOKURA, G SAITO

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   216-18   195 - 200   1992

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  • INVERSE PEIERLS TRANSITION INDUCED BY PHOTOEXCITATION IN POTASSIUM TETRACYANOQUINODIMETHANE CRYSTALS

    S KOSHIHARA, Y TOKURA, Y IWASA, T KODA

    PHYSICAL REVIEW B   44 ( 1 )   431 - 434   1991.7

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    DOI: 10.1103/PhysRevB.44.431

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  • ONE-DIMENSIONAL FERROELECTRICITY AND DYNAMICS OF DOMAIN-WALLS IN ORGANIC-COMPOUNDS

    Y MORITOMO, Y TOKURA, S KOSHIHARA, Y IWASA, T KODA, N IWASAWA, G SAITO, T OHASHI, T KOJIMA, A ITUSBO

    SYNTHETIC METALS   43 ( 1-2 )   3275 - 3278   1991.6

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  • NEUTRAL-IONIC TRANSITION IN TTF-CHLORANIL AND TMB-TCNQ

    Y IWASA, SOGA, I, T KODA, Y TOKURA, G SAITO

    SYNTHETIC METALS   42 ( 1-2 )   1827 - 1830   1991.5

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  • NONLINEAR SOLITON TRANSPORT IN CHARGE-TRANSFER COMPOUNDS

    Y IWASA, N WATANABE, T KODA, S KOSHIHARA, Y TOKURA, N IWASAWA, G SAITO

    SYNTHETIC METALS   42 ( 1-2 )   1675 - 1678   1991.5

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  • DOMAIN-WALL EXCITATIONS IN ORGANIC CHARGE-TRANSFER COMPOUNDS INVESTIGATED BY PHOTO-REFLECTANCE SPECTROSCOPY

    S KOSHIHARA, Y TOKURA, Y IWASA, T KODA, G SAITO, T MITANI

    SYNTHETIC METALS   42 ( 3 )   2351 - 2354   1991.5

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  • ANOMALOUS DIELECTRIC RESPONSE IN TETRATHIAFULVALENE-PARA-CHLORANIL AS OBSERVED IN TEMPERATURE-INDUCED AND PRESSURE-INDUCED NEUTRAL-TO-IONIC PHASE-TRANSITION

    H OKAMOTO, T MITANI, Y TOKURA, S KOSHIHARA, T KOMATSU, Y IWASA, T KODA, G SAITO

    PHYSICAL REVIEW B   43 ( 10 )   8224 - 8232   1991.4

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  • Inverse Peierls Transition Induced by Photoexcitation in Potassium Tetracyanoquinodimethane Crystals

    Physical Review B   44 ( 1 )   431 - 434   1991

  • Anomalous dielectric response in tetrathiafulvalene-p-chloranil as observed in temperature-and pressure-induced neutral-to-ionic phase transition

    OKAMOTO H, MITANI T, TOKURA Y, KOSHIHARA S, KOMATSU T, IWASA Y, KODA T, SAITO G

    Phys. Rev   43 ( 10B )   8224 - 8232   1991

  • Negative resistance effect in rubidium-tetracyanoquinodimethane(Rb-TCNQ)

    WATANABE N, Y IWASA, KODA T

    Phys. Rev   44 ( 20 )   11111 - 11119   1991

  • Nonlinear optical study of quasi-one-dimensional platinum complexes : Two-photon excitonic resonance effect

    IWASA Y, FUNATSU E, HASEGAWA T, KODA T, YAMASHITA M

    Appl. Phys. Lett   59 ( 18 )   2219 - 2221   1991

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  • Inverse Peierls transition induced by photoexcitation in potassium-tetracyanoquinodimethane crystals

    Phys. Rev   B44   8224 - 8232   1991

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  • Anomalous dielectric response in tetrathiafulvalene-p-chloranil as observed in temperature-and pressure-induced neutral-to-ionic phase transition

    Phys. Rev   43 ( 10B )   8224 - 8232   1991

  • Negative resistance effect in rubidium-tetracyanoquinodimethane(Rb-TCNQ)

    Phys. Rev   44 ( 20 )   11111 - 11119   1991

  • Nonlinear optical study of quasi-one-dimensional platinum complexes : Two-photon excitonic resonance effect

    Appl. Phys. Lett   59 ( 18 )   2219 - 2221   1991

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  • Inverse Peierls transition induced by photoexcitation in potassium-tetracyanoquinodimethane crystals

    Phys. Rev   B44   8224 - 8232   1991

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  • 有機錯体結晶の相転移と非線形電導現象

    応用物理   59   1272 - 1283   1990

  • 有機電荷移動錯体におけるソリトンダイナミクス

    岩佐 義宏, 国府田 隆夫

    固体物理   25 ( 4 )   259 - 266   1990

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  • Temperature-induced neutral-ionic transition in tetramethylbenzidine-tetracyanoquinodimethane

    IWASA Y, KODA T, TOKURA Y, KOBAYASHI A, IWASAWA N, SAITO G

    Phys. Rev   42 ( 4 )   2374 - 2377   1990

  • Electrical Switching Effect in Organic Charge-Transfer Compounds

    IWASA Y, WATANABE N, KODA T, KOSHIHARA S, TOKURA Y, IWASAWA N, SAITO G

    Molecular Crystals and Liquid Crystals   183   177 - 180   1990

  • Temperature-induced neutral-ionic transition in tetramethylbenzidine-tetracyanoquinodimethane

    Phys. Rev   42 ( 4 )   2374 - 2377   1990

  • Electrical Switching Effect in Organic Charge-Transfer Compounds

    Molecular Crystals and Liquid Crystals   183   177 - 180   1990

  • MAGNETIC-FIELD EFFECT ON THE STOKES SHIFT IN P-TYPE MODULATION-DOPED QUANTUM WELLS

    JS LEE, N MIURA, Y IWASA

    SOLID STATE COMMUNICATIONS   69 ( 3 )   293 - 296   1989.1

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  • Domain-wall dynamics in organic charge transfer compounds with one-dimensional ferro-electricity

    Phys. Rev. Lett   63 ( 21 )   2405 - 2408   1989

  • Intrinsic negative resistance effect in mixed-stack charge-transfer crystals

    Phys. Rev   39 ( 14 )   10441 - 10444   1989

  • Switching effect in organic charge transfer complex crystals

    IWASA Y, KODA T, TOKURA Y, KOSHIHARA S, IWASAWA N, SAITO G

    Appl. Phys. Lett   55 ( 20 )   2111 - 2113   1989

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  • Domain-wall dynamics in organic charge transfer compounds with one-dimensional ferro-electricity

    TOKURA Y, KOSHIHARA S, IWASA Y, OKAMOTO H, KOMATSU T, KODA T, IWASAWA N, SAITO G

    Phys. Rev. Lett   63 ( 21 )   2405 - 2408   1989

  • Intrinsic negative resistance effect in mixed-stack charge-transfer crystals

    IWASA Y, KODA T, KOSHIHARA S, TOKURA Y, IWASAWA N, SAITO G

    Phys. Rev   39 ( 14 )   10441 - 10444   1989

  • Switching effect in organic charge transfer complex crystals

    Appl. Phys. Lett   55 ( 20 )   2111 - 2113   1989

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  • MAGNETO-OPTICS OF N-TYPE AND P-TYPE MODULATION-DOPED GAAS/ALXGA1-XAS QUANTUM WELLS

    JS LEE, N MIURA, Y IWASA

    SURFACE SCIENCE   196 ( 1-3 )   534 - 539   1988.3

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  • Dynamical Aspects of Neutral-Ionic Phase-Transition in Organic Charge-Transfer Complex-Crystals

    Synthetic Metals   27   B189-B196   1988

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  • Dynamical Aspects of Neutral-Ionic Phase-Transition in Organic Charge-Transfer Complex-Crystals

    Synthetic Metals   27   B189-B196   1988

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  • THE MAGNETIC-FIELD-INDUCED INDIRECT EXCITON TRANSITION IN BII3 SINGLE-CRYSTALS

    K WATANABE, T KOMATSU, S TAKEYAMA, Y IWASA, N MIURA, Y KAIFU

    JOURNAL OF PHYSICS C-SOLID STATE PHYSICS   20 ( 36 )   6315 - 6323   1987.12

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  • FREE CARRIER EFFECTS ON EXCITON SPECTRA IN P-TYPE MODULATION-DOPED GAAS-ALGAAS QUANTUM-WELLS IN HIGH MAGNETIC-FIELDS

    Y IWASA, JS LEE, N MIURA

    SOLID STATE COMMUNICATIONS   64 ( 4 )   597 - 601   1987.10

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  • OBSERVATION OF THE FERMI EDGE ANOMALY IN THE ABSORPTION AND LUMINESCENCE SPECTRA OF N-TYPE MODULATION-DOPED GAAS-ALGAAS QUANTUM-WELLS

    JS LEE, Y IWASA, N MIURA

    SEMICONDUCTOR SCIENCE AND TECHNOLOGY   2 ( 10 )   675 - 678   1987.10

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  • Magnetooptical Properties of GaAs-AlGaAs Quantum Wells

    Iwasa Yoshihiro, Miura Noboru

    42 ( 7 )   643 - 646   1987

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    DOI: 10.11316/butsuri1946.42.643

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  • A MAGNETOOPTICAL ABSORPTION STUDY OF ALXGA(1-X)AS TERNARY ALLOY QUANTUM-WELLS

    S TARUCHA, H IWAMURA, T SAKU, H OKAMOTO, Y IWASA, N MIURA

    SURFACE SCIENCE   174 ( 1-3 )   194 - 199   1986.8

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  • CYCLOTRON-RESONANCE OF TWO-DIMENSIONAL HOLES IN GAAS-ALGAAS MULTI-QUANTUM-WELLS

    Y IWASA, N MIURA, S TARUCHA, H OKAMOTO, T ANDO

    SURFACE SCIENCE   170 ( 1-2 )   587 - 592   1986.4

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  • 超格子中2次元励起子の磁気光学

    固体物理   21   530 - 536   1986

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  • EXCITON BINDING-ENERGY IN GAAS QUANTUM WELLS DEDUCED FROM MAGNETO-OPTICAL ABSORPTION MEASUREMENT

    S TARUCHA, H OKAMOTO, Y IWASA, N MIURA

    SOLID STATE COMMUNICATIONS   52 ( 9 )   815 - 819   1984

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  • Frequency dependent Shubnikov-de Hass oscillations in Si-MOS-FET under high magnetic field

    Solid State Commun   46 ( 3 )   239 - 242   1983

  • Frequency dependent Shubnikov-de Hass oscillations in Si-MOS-FET under high magnetic field

    IWASA Y, KIDO G, MIURA N

    Solid State Commun   46 ( 3 )   239 - 242   1983

  • Shubnikov-de Hass effect in Si MOS-FET in high magnetic field up to 37T

    J. Phys. Soc. Jpn   51 ( 4 )   1228 - 1235   1982

  • Shubnikov-de Hass effect in Si MOS-FET in high magnetic field up to 37T

    MIURA N, IWASA Y, ITAKURA T, KIDO G

    J. Phys. Soc. Jpn   51 ( 4 )   1228 - 1235   1982

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Works

  • 有機材料による界面制御

    2006 - 2011

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  • 有機半導体基礎伝導

    2006 - 2011

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  • 有機伝導性化合物の探索

    2003

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  • 有機トランジスタの研究

    2003

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  • Search for novel conducting organic compounds

    2003

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  • カーボンナノチューブの光機能の研究

    2002

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  • ナノクラスターの配列・配向制御による新しいデバイスと量子状態の創出

    2001 - 2006

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  • フラーレン・ナノチューブネットワーク

    1998 - 2000

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  • フラーレン・ナノチューブなどナノメターター人工物質の探索と物性

    1996 - 2000

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  • フラーレン化合物の構造と物性

    1996

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Awards

  • 文部科学大臣表彰 科学技術賞 研究部門

    2014  

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  • 第14回超伝導科学技術賞

    2010  

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  • 矢崎学術功績賞

    2007  

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    Country:Japan

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  • 第29回応用物理学会論文賞

    2007  

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    Country:Japan

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  • 日本IBM科学賞

    2004  

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    Country:Japan

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  • Daiwa Adrian Prize

    2004  

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    Country:Japan

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  • 金属材料科学助成賞

    2002  

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    Country:Japan

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Research Projects

  • Physics and Functions of van der Waals Heterostructures

    Grant number:19H05602  2019.6 - 2024.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (S)

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    Grant amount:\200980000 ( Direct Cost: \154600000 、 Indirect Cost:\46380000 )

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  • ファンデルワールス・ヘテロ接合を用いた非相反現象と電子相制御の研究

    Grant number:19H00653  2019.4 - 2020.3

    日本学術振興会  科学研究費助成事業  基盤研究(A)

    岩佐 義宏

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    Grant amount:\46150000 ( Direct Cost: \35500000 、 Indirect Cost:\10650000 )

    本研究は、ファンデルワールス(VdW)ヘテロ接合による物性の制御を目的としており、主に機械的な積層法によって、多様なvdWヘテロ接合を作製する。本年度は、MoS2単層と多層黒リン(BP)の積層構造の作製と、対称性を反映する異常光電流(ゼロバイアスでの光電流)の評価を行った。MoS2単層は三回回転対称性を有する物質であり、BPは二回回転対称性を持つが、これらの回転対称性は両立することができないため、vdWヘテロ接合では回転対称性が消失し極性界面が現れると考えられる。とくに両物質が有する鏡面をそろえて積層した場合には、鏡面方向に極性が生ずる。本研究では両物質の鏡面を0度、および90度の角度で積層した2種類の界面を作製し、それからの光電流マッピングを行った。その結果、鏡面を0度で積層した場合に、光電流が界面全体で発生することが観察され、極性を持たない2つの物質の界面において極性が発生していることを強く示唆する結果を得た。さらに、分極に平行方向での光伝導度が現れる一方、極性に垂直方向での光電流は比較的弱いという結果も得られた。さらに、カナダのブリティッシュコロンビア大学との共同研究を行い、光電流の励起スペクトルを測定した。その結果、MoS2のバンドギャップより大きな光エネルギー領域で特徴あるピークを観測するとともに、バンドギャップより小さな光エネルギー境域では、分極に垂直な方向の光電流が、平行な方向よりも大きくなる逆転現象を発見した。
    これらの結果を受け、理論家と協力して、MoS2/BP界面のバインディングモデルによる定式化を行うとともに、シフト電流機構による非線形光伝導度の励起スペクトルの計算を行った。励起スペクトルには、実験との定性的な一致が見られ、計算が本系の本質をとらえているとともに、シフト電流機構を強く支持する結果が得られた。

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  • イオントロニクス学理の構築

    Grant number:25000003  2013 - 2018

    日本学術振興会  科学研究費助成事業  特別推進研究

    岩佐 義宏, 秋光 純, 渡邉 正義, 塚崎 敦, 竹延 大志

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    Grant amount:\614120000 ( Direct Cost: \472400000 、 Indirect Cost:\141720000 )

    2018年度は、最終年度の2017年度からの予算繰り越しによって、岩佐グループのみに研究費を配分した。岩佐は、下記の成果を上げた。塚崎と竹延は、独自に研究を継続し、最終年度にふさわしい、意義ある共同研究成果を出版した。
    まず岩佐は以下の津3つの成果を上げた。
    ①イオントロニクス技術の一つに、単一試料におけるキャリア数制御を通した電子相図の構築があるが、この技術を電子ドープ型銅酸化物に適用し、アンダードープ領域からオーバードープ領域までの電子相図を構築することに成功した。その過程で、超伝導相が立ち上がる近傍で電荷密度波相が発達することを発見した。
    ②また、イオントロニクス法による電界誘起超伝導を推進した。電気化学的手法によってイオンをドープした、単一遷移金属ダイカルコゲナイドナノチューブ電界誘起超伝導の研究を進め、超伝導転移温度とナノチューブの直径依存性を明らかにした。また、電界誘起2次元超伝導における、結晶対称性の破れに起因する超伝導の整流性を研究した。超伝導の整流性の特徴的な振る舞いが超伝導ボルテックスの量子的な運動によって理解できるをことを発見した。
    ③一方で、分子線エピタキシー法で2次元物質やそのヘテロ構造を作製する手法を確立した。そして、フェルミ準位の異なる2次元物質を積層させた界面では、フェルミ準位の差に依存して電荷移動が生じ、組み合わせによっては元々が絶縁体同士でも高い電気伝導性を示す電荷移動界面を構築可能であることを発見した。
    次に塚﨑らは、イオン液体を用いた電気化学エッチングを推進した。2018年度は、岩佐グループとの共同研究を進め、FeSe原子層状態の超伝導特性と熱電特性の相関を明らかにした。その結果、原子層おいて、巨大な熱電変換効率を示すことを発見した。実現された熱電電力因子は室温において250μW/cm/K^2、低温の45 Kにおいて250mW/cm/K^2に達した。すなわち、室温以下での熱電電力因子の世界記録をイオントロニクスによって達成できたのである。本研究は2次元物質の隠された性能をイオントロニクスによって引き出した極めて重要な成果である。
    竹延らは、電解質を用いた発光素子をGaN、有機高分子、遷移金属ダイカルコゲナイド単層膜などで実現した。加えて、グラファイト、有機高分子のフィリング制御し、熱電変換特性を明らかにした。電解質を用いつつ、大面積で将来的に集積化可能な集積化可能なインバータの作製にも成功している。

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  • Elucidation of device operation and degradation mechanism of low voltage ion gel-gated organic transistors from microscopic viewpoints and performance improvement

    Grant number:24560004  2012.4 - 2015.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    MARUMOTO Kazuhiro, TAKENOBU Taishi, IWASA Yoshihiro, AZUMI Reiko

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    Grant amount:\5070000 ( Direct Cost: \3900000 、 Indirect Cost:\1170000 )

    We applied an electron spin resonance (ESR) method to low voltage ion gel-gated organic transistors to clarify the operation and degradation mechanisms of the devices under high charge density conditions through microscopic characterization by ESR under device operation. The ESR method is high sensitive and capable of characterizing materials at the molecular level. Using the ESR method, we studied electronic states of charge carriers in organic materials, such as spin states and magnetic interactions among carriers, as a function of gate voltage in detail. As a result, we clarified the phenomena of the dimensionality variation in the magnetic interactions from zero-dimensional to two- or three-dimensional and the realization of the complete nonmagnetism with increasing charge density.

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  • Novel phenomena in electronic fluids with broken inversion symmetry

    Grant number:22103004  2010.4 - 2015.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

    ZHENG Guo-qing, UENO Kazunori, SEGAWA Kouji, NOJIMA Tsutomu, INADA Yoshihiko, SHISHIDOU Tatsuya, ANDO Yoichi, NAGAOSA Naoto, IWASA Yoshihiro, HANAGURI Tetsuo, OSADA Toshihito, MATANO Kazuaki, YOKOYA Takayoshi

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    Grant amount:\246870000 ( Direct Cost: \189900000 、 Indirect Cost:\56970000 )

    In the electronic fluids with broken inversion symmetry and strong spin-orbit coupling, we have investigated various topological quantum phenomena and obtained the following results. In noncentrosymmetric superconductors, we clarified the conditions necessary for bringing about a large spin-triplet component. We have succeeded in synthesizing new topological insulators and found that CuxBi2Se3 is a spin-triplet superconductor. We discovered electric-field-effect induced superconductivity in KTaO3 which cannot be made superconducting by conventional chemical doping method.

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  • Study on aromatic hydrocarbon superconductors

    Grant number:22244045  2010.4 - 2015.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    KUBOZONO YOSHIHIRO, KAMBE Takashi, IWASA Yoshihiro, OKAMOTO Hideki

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    Grant amount:\46540000 ( Direct Cost: \35800000 、 Indirect Cost:\10740000 )

    The first discovery of superconductivity in solids of metal doped aromatic hydrocarbons was made for K-doped picene (Kxpicene). Its superconducting transition temperatures (Tc's) were 7 and 18 K. During this project, we pursued to make new superconductors using aromatic hydrocarbons. Various techniques such as high-temperature annealing method, liquid ammonia method, and electrochemical process were used for metal doping. The superconducting phases of Kxpicene and Rbxpicene exhibiting more than 10% superconducting fraction were successfully prepared in this project. The zero-resistance was confirmed in Kxpicene. With applying pressure, the Tc of 7 K phase of Kxpicene monotonically decreased, while the Tc's of 14 and 18 K phases increased, implying that 14 and 18 K phases are non-BCS type. Furthermore, superconductors were fabricated by doping various types of phenacene molecules with metals. The chemical composition and crystal structures of superconducting phases were investigated.

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  • Control of Electronic Properties of Materials Using Ultrahigh Electric Field at Electrochemical Interfaces

    Grant number:21224009  2009.5 - 2014.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (S)

    IWASA Yoshihiro, NOJIMA Tsutomu, TAKENOBU Taishi, SHIMOTANI Hidekazu, KASAHARA Yuichi, UENO Kazunori, TAKEYA Jun

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    Grant amount:\219050000 ( Direct Cost: \168500000 、 Indirect Cost:\50550000 )

    We have developed electric double layer transistor (EDLT) devices, which allows us a high density carrier accumulation exceeding the limit of all solid field effect transistors, taking the advantage of the ultrahigh electric field generated at the electrochemical interfaces. We applied this technique to a wide range of materials including bulk crystals, thin films, and nanodevices fabricated by an exfoliation method combined with electron beam lithography. We succeeded in electrical phase control of superconductivity, ferromagnetism, and Mott-Hubbard transitions in various materials, among which we were able to encounter novel phenomena which are impossible in conventional all solid field effect transistors. We also found novel functions of EDLTs, such as electrical control of spin polarization and flexible devices, all of which indicates that EDLT is an extremely powerful technique to further broaden materials science.

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  • Charier density control and charge/spin dynamics in layered nitride superconductors

    Grant number:19204036  2007 - 2008

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    TAGUCHI Yasujiro, TOU Hideki, IWASA Yoshihiro

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    Grant amount:\35490000 ( Direct Cost: \27300000 、 Indirect Cost:\8190000 )

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  • カーボンナノチューブのテラヘルツー遠赤外物性と機能開拓

    Grant number:18654059  2006 - 2007

    日本学術振興会  科学研究費助成事業  萌芽研究

    岩佐 義宏

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    Grant amount:\3300000 ( Direct Cost: \3300000 )

    カーボンナノチューブの吸収スペクトルには、テラヘルツ領域に強い強度を有するピーク構造が観測される。このピークは、金属ナノチューブのバンドル化による擬ギャップ、らせん度に起因したナローギャップとの解釈が一般的であった。昨年度、本グループでは、カーボンナノチューブ配向薄膜を作成し、その広領域分光を行った。その結果、テラヘルツ領域でのピーク構造が強く変更依存性をもつことから、このピークが金属ナノチューブに由来するものであることを確認するとともに、モルホロジ依存性などからこのピークが、従来のモデルのような電子構造に由来するものではなく、長さに依存するプラズモンピークであることを提唱した(N.Akima et al. Adv. Mater. 18,1166(2006))。
    本年度は、酸によるエッチング法を用いたカーボンナノチューブの長さを制御する方法を確立し、長さの異なるカーボンナノチューブ配向薄膜の作製に成功した。これを用いた分光測定によって、テラヘルツ領域のピーク位置が長さ依存性をもち、チューブが短くなるとピーク位置が高エネルギー側にシフトすることを見出した。これは、前年度提出した、プラズモンモデルを強く支持する結果である。この原理を利用すると、カーボンナノチューブの長さを見積もりに使える可能性があり、テラヘルツ応答の測定が新しいナノチューブの評価法として有効になると期待され、本萌芽研究は、極めて興味深い展開をもたらし始めたと結論できる。これを定量的に実証するため、現在、有限長ナノチューブの電磁応答に関する理論的検討を産総研のグループと行っている。

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  • Interface control and carrier transport in molecular materials

    Grant number:17069003  2005 - 2009

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Priority Areas

    IWASA Yoshihiro, TAKENOBU Taishi, SHIMOTANI Hidekazu, KASAHARA Yuichi, TAKEYA Junichi

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    Grant amount:\78700000 ( Direct Cost: \78700000 )

    By means of nanoscled interface control in organic field effect transistors (OFETs), we have achieved following four major achievements, all of which make important benchmarks. (1)The highest mobility of 40cm^2/Vs among organic FETs. (2)First measurement of Hall effect on OFETs. (3)First realization of ambipolar light emitting transistor of organic single crystals. (4)Highest transconductance among OFETs using the electric double layer configuration.

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  • Control of electronic and optical properties in nanomaterials and their functional interfaces

    Grant number:17204022  2005 - 2008

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    IWASA Yoshihiro, TAKENOBU Taishi, TAGUCHI Yasujiro, KOBAYASHI Shinichiro, SHIMOTANI Shimotani, KASAHARA Yuichi

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    Grant amount:\46930000 ( Direct Cost: \36100000 、 Indirect Cost:\10830000 )

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  • Superconductivity of carbon and related-orbital systems

    Grant number:16076201  2004 - 2008

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Priority Areas

    SAITO Riichiro, FKUYAMA Hidetoshi, IWASA Yoshihiro, SASAKI Takahiko, FKUYAMA Hidetoshi

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    Grant amount:\57000000 ( Direct Cost: \57000000 )

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  • Synthesis and phase control of fullerene based superstructured materials

    Grant number:15340106  2003 - 2004

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    TAGUCHI Yasujiro, IWASA Yoshihiro

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    Grant amount:\14400000 ( Direct Cost: \14400000 )

    In this fiscal year, we have tried to reveal universality and unique points in fullerene based compounds, dealing with layered nitride superconductors that also exhibit band insulator to superconductor transition similarly to the case of alkali metal intercalated fullerides. We have succeeded in preparing a series of samples with continuously changed Li-content (x<0.12), and have confirmed that these are of single phase by using synchrotron X-ray diffraction technique at BL2B-02, SPring 8. This fact makes striking contrast with the case of fullerides where only line phases exist and the intermediate phases can not be obtained, clearly indicating the anomalous solid state chemistry of fullerene compounds. Also, we have performed the specific heat measurements of layered nitride superconductors in magnetic fields, and have found that the normal-state Sommerfeld constant γ is very small (=1.0 mJ/mol K^2). We can obtain very small electron-phonon coupling constant λ(=0.22) by using this value and the density of states at the Fermi level predicted by several band calculations. This fact is in accord with the relatively narrow phonon lines observed in Raman scattering spectra. This fact also makes striking contrast with the fullerides where superconductivity is mediated by high frequency phonon with intermediate electron-phonon coupling strength, indicating the importance of Jahn-Teller interaction where the fullerene molecules show deformation. It is theoretically pointed out that Jahn-Teller interaction that couples with the degenerate LUMO orbitals is important in fullerides, and our result is consistent with this.

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  • Physical Properties of Endohedral Metallo fullerenes at solid, thin film and nano-scale.

    Grant number:15350089  2003 - 2004

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    KUBOZONO Yoshihiro, IWASA Yoshihiro, TAKAYANAGI Toshio

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    Grant amount:\13200000 ( Direct Cost: \13200000 )

    The structures and electronic properties of endohedral metallofullerenes and higher fullerenes have been studied at solid, thin-film and nanometer scale. The crystal structures of M@C_<82>(Dy,Ce and Pr) and C_<82> have been determined to be simple cubic (Pa3) by Rietveld refinements for X-ray diffraction patterns with synchrotron radiation. The first-order structural phase transition was observed for the crystals of M@C_<82> around 150 K. Furthermore, Rb_<8.8(7)>C_<84> was prepared by doping Rb metal into the crystals of C_<84>, and the X-ray diffraction pattern showed the simple cubic structure of Pa3. The temperature-dependent ESR spectra suggested a metallic behavior for Rb_<8.8(7)>C_<84>.
    The resistivity and optical absorption spectra for M@C_<82>,C_<82> and C_<84> showed that these compound are not metals but normal semiconductors with small gap. The gap estimated from resistivity was 1/2 of the optical gap. Therefore the gap estimated from resistivity was concluded to be mobility gap. The thin-film field-effect transistors (FETs) have been fabricated with M@C_<82>,C_<82>,C_<84> and C_<88>. These FETs showed n-channel normally-on FET properties. The field-effect mobility of C_<88> FET reached to 〜10^<-2> cm^2 V^<-1> s^<-1>, whose value was the second highest value among the fullerene FETs. The normally-on properties for endohedral metallofullerens and higher fullerenes originate from high bulk current which flow in all region of thin films.
    The scanning tunneling microscope(STM) showed clear images of local structures of M@C_<82> inclusive of internal structures. The growth of M@C_<82> on well-defined Si(111)-(7 x 7) surfaces has been fully studied by the STM, and the Stranski-Krastanov type growth was found for M@C_<82>. The M@C_<82> molecules in the first layer are strongly bound on the Si surface through the chemical bond between C atoms and dangling bonds of Si adatoms. The M@C_<82> molecules above the first layer aggregate by van der Waals force between molecules. The close-packed structures of M@C_<82> have been formed by annealing the Si substrates covered with multilayer of M@C_<82> at 200℃.
    The removals and movements of C_<60> molecules in the close-packed layer of C_<60> have been achieved at single molecular precision by field evaporation with the STM tip. The pin-point shooting from the STM tip enables ones to draw nano-scale characters, pictures and patterns consisting of molecular size voids. Because of technical simplicity, the free controllability, and 1 nm size of voids, this technique is widely applicable to nanoscale manufacture. Thus much information of the structures and physical properties of endohedral metallofullerens and higher fullerenes has been obtained, and the applications towards thin-film FET devices and molecular electronics have been tried based on the obtained information.

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  • 層状化合物の超伝導物性

    2002

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    Grant type:Competitive

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  • Superconductivity in layered materials

    2002

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    Grant type:Competitive

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  • Phase Control of Fullerene Materials through Chemical Synthesis and Field Effect Doping

    Grant number:13440110  2001 - 2003

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    IWASA Yoshihiro, KOBAYASHI Shinichiro, TAHENOBU Taishi, TAGUCHI Yasujiro, IZUMI Akira

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    Grant amount:\17000000 ( Direct Cost: \17000000 )

    Organic thin film transistors (TFTs) are attracting a great deal of attention due to the relatively high field-effect mobility in several organic materials. In these organic semiconductors, however, researchers have not established a reliable method of doping in a very low density level, although this has been crucial for technology development of inorganic semiconductors. Here we discuss a new technique that enables us to control the charge density at the channel by employing organosilane self-assembled monolayers (SAMs) on SIO_2 gate insulators. SAMs with fluorine and amino groups have been shown to accumulate holes and electrons, respectively, in the transistor channel : These properties are understood in terms of the effects of electric dipoles of the SAMs molecules and weak charge transfer between organic films and SAMs.
    In-situ high pressure x-ray diffraction experiments and the first-principle local density functional calculations revealed that a transformation from the two-dimensional (2D) tetragonal C60 polymer to a three-dimensional (3D) polymer takes place via. a highly anisotropic compression of C60 molecules along the c-axis, as an irreversible first-order order transformation above 20 GPa. In the 3D polymer phase, the 2+2 bonds remains in the 2D plane, while neighboring layers are connected by the 3+3 bonds. The bulk modulus of the 3D polymer was 407 GPa, being slightly smaller than that of diamond.

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  • Search for Novel Carbon Based Nanonetwork Materials and their Properties

    Grant number:11165218  1999 - 2000

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Priority Areas (A)

    IWASA Yoshihiro, AHN J-s

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    Grant amount:\43900000 ( Direct Cost: \43900000 )

    (1) Intercalation processes of carbon nanotubes with alkali metals
    One of the possible application of single walled carbon nanotubes (SWNT) is the anode of the Li ion batteries. We have uncovered the intercalation processes by means of the spectroscopic methods, such as Raman, infrared, and XPS. First, alkali metals are inserted into interstitial sites surrounded by three tubes, followed by an insertion into the smaller site between two tubes, causing a serious expansion of the intertube distances. Until this state, A3C80, the concentration of alkali metals increases continuously, but displays a discontinuous jump to A9C80, above which the A concentration shows a continuous increase again.
    (2) Molecular orientations and magnetic structures in fullerene antiferromagnets
    We have systematically synthesized (NH_3)A_3C_<60>, by intercalating neutral ammonia molecules into A_3C_<60> superconductors, and found that all the monoammoniated compounds are antiferromagnetic insulators. (NH_3)A_3C_<60> adopts an orthorhombic unit cell derived by a slight deformation of the fcc cell of A_3C60, and because of this deformation, the electron is localized on the C_<60> moiety. Furthermore, the magnetic structure and molecular orientations have been determined by NMR, and neutron scattering experiments, respectively. The correlation between these displays a nice analogy to the relation between the orbital and spin orderings in transition metal oxides magnets, which is known as Kanamori-Goodenough rule.
    (3) Novel dimer structure in rare earth metal doped fullerides
    Intercalation of fullerenes with rare earth metals has been investigated. Among these, we succeeded in synthesizing single phase Sm_3C_<70>, and in determining the crystal structure in a electron density level, by means of MEM/Rietveld analysis. It was found that two neighboring C_<70> moieties are connected by the Sm ion, forming a new type of dimer structure. This dimer structure is considerably stable, because the structure is maintained at least up to 850K, in contrast to the bond breaking in the conventional fullerene polymers showing a bond breaking below 600K.
    (4) Dielectric properties of La@C_<82> thin films
    We have fabricated thin films of the metallofullerene La@C_<82>, and measured dielectric constants as a function of temperature. The dielectric constant at room temperature is about 40, approximately one order larger than that of C_<60> (4.4). The considerably large dielectric constant is presumably due to the rotation of the molecules with a large dielectric moment. Such dipolar activity of La@C_<82> might suggest that the molecular rotation states could be controlled by the external electic field.

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  • Electronic states of metal nanoparticles investigated by far infrared spectroscopy

    Grant number:11640312  1999 - 2000

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    IWASA Yoshihiro, TERANISHI Toshiharu, MIYAKE Mikio, MITANI Tadaoki

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    Grant amount:\3300000 ( Direct Cost: \3300000 )

    The most important result of this project is the successful synthesis of monodispersed nanoparticles of platinum, palladium, and gold. For organic lgands which stabilizes metal nanoparticles, we used PAA or PVP for PT and Pd, while DT was useful for gold systems.Particularly, we have succeeded in fabricating two-dimensional monolayers of gold nanoparticles forming a hexagonal lattice. Furthermore, two-dimensional superlattice and three-dimensional aggregates were successfully constructed with use of interligand bridging by Fe^2 ions. We have also obtained important information on magnetic and spectroscopic properties. We found several series of absorption peaks in the far infrared spectra, which are not assigned to the absorption of Organic ligands. These peaks are most likely attributed to the transitions between quantized electronic levels in nanoparticles. A quantitative analysis based on the Woods-Saxon potential is underway,

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  • フラーレンナノチューブネットワーク

    Grant number:10184101  1998 - 2000

    日本学術振興会  科学研究費助成事業  特定領域研究(A)

    斎藤 晋, 菊地 耕一, 岩佐 義宏, 安藤 恒也, 齋藤 弥八, 小林 本忠

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    Grant amount:\50300000 ( Direct Cost: \50300000 )

    領域内の研究情報交流及び研究成果の公開を目的としたニュースレターを発行し、さらに、領域ホームページを開設した。また、総括班主催の研究会として全項目が参加し、討議時間を十分に取った公開形式のワークショップを4回開催した(1999年11月三重県、2000年2月東京、2000年6月姫路、2000年10月金沢市)。この様な公開型ワークショップに加え、計画研究参加者による顔合わせ研究会、公募研究課題が決定した段階での研究会も開催した。これらの研究集会は、理学・工学の幅広い分野から多様な研究者が本特定領域に参加していることによる、コミュニケーションの障害となり得る「言葉」(専門用語)の問題を解決することに役立てることも大きな目的であった。そして、参加研究者間で、多くの共同研究が展開され、これら総括班活動の主目的は達成されたと判断される。
    本特定領域研究による成果を国際研究コミュニティに発信すること、さらに、本領域が、欧米各国でも、最重点領域として研究展開がはじめられたことから、我が国研究者のリーダーシップの確保をも目的として、国際会議International Symposium on Nanonetwork Materials:Fullerenes,Nanotubes,and Related Systems(ISNM2001)を、2001年1月に開催した。この会議は、参加者総数220名と盛況となり、かつ講演レベルも非常に高く、充実した催しとなった。参加者内訳でも海外から50名の参加者があり、国際会議と呼ぶに相応しい内容であり、上記開催目的を達成することができた。

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  • 高機能薄膜の分光学的研究

    Grant number:09045031  1997 - 1998

    日本学術振興会  科学研究費助成事業  国際学術研究

    水谷 五郎, 佐野 陽之, 北川 宏, 岩佐 義宏, 三谷 忠興, デイ ピーター

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    Grant amount:\4500000 ( Direct Cost: \4500000 )

    本年度は、新機能材料の設計と試作評価、及び基礎物性の解明を目指し以下の研究を行った。
    1. BEDT-TTF(ET)系ドナー分子を構成要素として用いた交互積層型電荷移動錯体である(ET)(CIMeTCNQ)の合成を行った。このET系交互積層型電荷移動錯体は、従来型の一次元性の強い錯体とは対照的にETに特徴的なside-by-side相互作用により格子の二量化が抑制されるため、イオン性錯体がキュリー常磁性を示し、ラジカルスピンの自由度が生き残るという特徴をもつ。この物質の近赤外-可視領域の光学吸収スペクトルの圧力依存性の測定を行い、中性-イオン性転移を起こすことを発見した。
    2. 低温まで安定な金属状態を得ることができるBETS-X_1X_2TCNQ(X_1,X_2=Br,CI)錯体の柱状結晶の作成に成功し、その極低温高圧物性に関する系統的研究を行った。(BETS)_2(Br_2TCNQ)では14Kで金属-絶縁体転移を起こし、転移点以下ではバンド構造が半導体的に変化することがわかった。
    3. 光触媒である酸化チタン(TiO_2)の触媒反応下での表面電子状態を調べるために、水蒸気雰囲気中紫外線照射下で氷分解反応が起こっているTiO_2表面の非線型光学応答の測定を行った。紫外線照射によって、第二高調波(SH)光の強度が約2倍増大することがわかった。また、SH光強度の試料方位角依存性の形は紫外線照射前後で変化しないことから、紫外線照射中の表面の波動関数の形は照射前と同じであり、紫外線照射によってできた表面の酸素欠陥が、表面電子状態の占有状態と非占有状態間の光学遷移を増大させていることがわかった。

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  • 有機・無機ハイブリッド化合物におけるプロトン-電子連動の光制御

    Grant number:08454220  1996 - 1998

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    三谷 忠興, 安 正道, 北川 宏, 岩佐 義宏

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    Grant amount:\8400000 ( Direct Cost: \8400000 )

    水素結合ネットワークを利用して結晶構造を制御しながら、同時に水素結合と強い相関をもつ電子状態を創造すると、そこには電子と水素結合間の相互作用に基づく新しい機能性が生まれる可能性があり、これらの物性探索は興味ある研究対象である。本研究の目的は、水素結合を含む有機無機ハイブリッド化合物を対象として、そこでの電子-プロトン相互作用の内容を解明するとともに、この相互作用を化学的および光学的に制御することによって生まれる新しい素子機能の開発を行うことにある。
    本研究においては特に[Pd(H2EDAG)-(HEDAG)]TCNQの水素結合型一次元電荷移動錯体に注目し、極低温や超高圧の条件を含めたX線構造解析、可視・赤外・遠赤外分光(吸収、反射、発光および光誘起吸収反射測定)、ラマン散乱、電気抵抗測定、光電導測定、ESR、光誘起ESR、帯磁率測定等、広い視野からの基礎物性研究を行った。その中で注目される研究成果は、結晶育成中において溶液中のpH濃度を制御することにより、結晶が脱プロトンされた不完全なイオン結晶;[Pd(H2-xEDAG)(HEDAG)]-(HEDAG)(HEDAG)]+(1-x)TCNQ-(1-x)(x=0.7)が得られ、180Kにおいて水素結合格子の融解、つまり、固体中でも溶液中と同じようなプロトンの"ゆらぎ"が生じると共に、ヒステリシスをもった金属-絶縁体相転移が観測されたことである。この結果は、温度因子の解析も含めたX線構造解析および半経験的分子軌道計算の結果と定性的に一致する。これらの実験事実は、電子-プロトン連動に基づく新しいタイプの電磁応答性、さらにはレーザ光による物質変換の可能性を実証するものである。

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  • Synthesisand properties of C_<60> based mutielement compounds

    Grant number:08454095  1996 - 1997

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    IWASA Yoshihiro, MITANI Tadaoki

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    Grant amount:\7900000 ( Direct Cost: \7900000 )

    We have carried out a fundamental research on fullerene based solids and obtained the following results.
    1. Fullerene polymers
    We have succeeded to selectively synthesize a fullerene dimer, which is a 2+2 cycloadduct of C60, by a high pressure-high temperature treatment of a molecular compound(ET)2C60. Comparing the dimer, one-dimensional polymer, and two-dimensional polymers by means of differential scanning calorimetry measurements, we clarified that all the polymeric forms of fullerenes are more stable than the monomer form. The energetics of the fullerene polymers are established in this work. The energy difference between these polymeric phases are smaller than the difference between graphite and diamond.
    2.Multinary fullerene superconductors
    2-1 : Antiferromagnetic order in NH3K3C6O
    Superconductor-insulator transition is one of the universal and fundamental problems in solid state physics.In the case of fullerenes, this transition takes place by an intercalation of NH3 molecules into superconducting K3C60. We have investigated the nonsuperconducting NH3K3C6O by various means to clarify the mechanism of superconductor-nonsuperconductor transition. We found that the electronic ground state of NH3K3C6O is an antiferromagnetic insulator. This result clearly shows that he loss of superconductivity in NH3K3C6O is of magnetic origin, providing a nice analogy to the well know cuprate and organic superconductors.
    2-2 : High pressure effect of (NH3)xNaA2C6O(O.5<x<l, A=K, Rb)superconductors
    The title superconductors shows an anomalous correlation between Tc and lattice parameter, which is opposite to the one found in the standard A3C60 superconductors. The Tc/llattice parameter correlation was investigated under hydrostatic pressure, showing that Tc of these ammoniated superconductors is not scaled any more simply by the interfullerene spacings.
    2-3 : Superconductor at highly doped states
    New fullerene superconductors with highly doped states are found. The nonavalent K3Ba3C6O and decavalent K2Ba4C6Oshowed that the criterion of superconductivity in the highly doped state is significantly different form that of the low doped systems.

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  • Development of 3-Dimensional X-ray Diffraction Technique for Fine Analysis of New Functional Materials.

    Grant number:08554029  1996 - 1997

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    MITANI Tadaoki, TORIUMI Koushiro, KAWAMURA Haruki, KITAGAWA Hiroshi, IWASA Yoshihiro

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    Grant amount:\10200000 ( Direct Cost: \10200000 )

    The aim of this project is to develop 3-dimensional X-ray diffraction techniques for detailed analysis of new functional materials. By applying the imaging plate method, an automatic control of total diffraction signals, and an inside beam-stoppermechanism, a fine X-ray diffraction analysis is achieved down to ca. 10K within 1% of the R factor. In addition, programs to visualize several physical parameters obtained by the X-ray analysis have been developed, and a new system for proving molecular mechanisms in complicated functional materials is obtained. The first application of this system was successfully made to study the cooperation of electron and proton in organic-inorganic hybrid systems : The electron-proton-cooperative systems of 1-D halogen-bridged metal (M=Ni, Pd, Pt) complexes and 1-D metallic charge-transfer crystals of Pd (H_<2-x>EDAG) (HEDAG)] TCNQ (EDAG=ethylenediaminoglyoxime, x=ca, 0.7) were focused. In the later crystals, the detailed experimental results of the X-ray diffraction meaurements are reported. Below the metalimsulator (M-1) phase transition (180K), commensurate superlattice reflections were observed with a period of with a period of c^*/2, c^*/3, and c^*/12 along the 1-D axis, c. The full X-ray diffraction analyzes of temperature-dependentreflections ignoring the superlattice points show remarkable increases of the structure factors below 180K for several atoms which associate with the intermolecular H-bonds between donor-molecules, (H_<2-x>EDAG) - (HEDAG). This is a result of cooperation between the order-disorder transition of the 1-DH-bond intermolecular superlattice and the M-1 transition of the 1-D electronic state in TCNQ acceptor stacks. These experimental results support a model of the electron-proton cooperation model proposed by the authors previously.

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  • 高圧を用いたC_<60>化合物の新物質新物性探索

    Grant number:07213102  1995

    日本学術振興会  科学研究費助成事業  重点領域研究

    岩佐 義宏, 有馬 孝尚

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    Grant amount:\2100000 ( Direct Cost: \2100000 )

    本研究では、フラーレンポリマーの開発と、多元複合化合物による新超伝導体の開発を行い、以下の成果を得た。
    [1]C70ポリマーの高圧合成
    C70を5GPa,300℃で処理すると、トルエンに溶解しない新物質が生成することを発見した。x線回折パターン、赤外振動スペクトルなどの実験データと分子軌道計算に基づく振動スペクトルの計算から、C70のダイマーを基本単位とする物質であることがわかった。フラーレン分子間での弱い化学結合の発生はC60に限らない一般的な現象であることがわかった。
    [2]アルカリドープC60ポリマーの合成
    C60の2次元ポリマー(菱面体構造)にNaイオンがドープされた新物質を合成した。C60・2次元ポリマーへのド-ピングの成功は今回が始めてである。組成式はNaC60であり、八面体サイトにNaイオンが存在すると考えられ、この点は四面体サイトにNaが集要されている分子結晶相と対照的である。
    [3]新超伝導体K3Ba3C60の合成
    Ba3C60にKをドープすることにより、Tc=5.6Kを有する新超伝導体K3Ba3C60の合成に成功した。超伝導体積分立は30%以上を示し、バルクの超伝導体であることが確認された。この超伝導体は第2LUMO由来の伝導体がハーフフィルド状態にある物質である。
    [4]新超伝導体(NH3)xNaA2C60(A=K,Rb)の合成
    液体アンモニアによる低温合成によって新超伝導体(NH3)xNaA2C60(A=K,Rb)の合成に成功した。この物質はアンモニア組成によって格子定数を制御できるが、格子定数が増加するとTcが低下するという従来にない傾向を示した。この物質はBCS弱結合領域から逸脱している可能性がある。

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  • ペロブスカイト型金属ハロゲン化物のフィリング制御と超伝導探索

    Grant number:07640467  1995

    日本学術振興会  科学研究費助成事業  一般研究(C)

    岩佐 義宏, 北川 宏

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    Grant amount:\2100000 ( Direct Cost: \2100000 )

    本研究では、混合原子価を示すペロブスカイト型金属ハロゲン化物ABX_3(A=K,Rb,Cs;B=Ag,Au;X=Cl,Br,l)を母体として、物質開発を行った。バンドフィリング制御の観点からは、A,Bサイト置換が必要不可欠である。
    (1)Aサイト置換、Bサイト置換
    アルカリ土類金属のBaを用いて、Aサイト置換を試みた。Bal_2とCsAul_3を用いてブリッジマン電気炉で合成を行った。黒色のサンプルを得たが、非常に不安定な物質で容易にヨウ素を遊離して分解する。今のところ精密な物性測定は成功していない。Bサイト置換については、同じくペロブスカイト構造を有する金属ハロゲン化物が有望である。この観点から、CsHg(5d^<10>)l_3とCsPb(5d^<10>6s^2)l_3に注目した。まずこれらの試料の合成を行い、CsAul_3と混合して電気炉で焼いた。各組成比においてCs(AuPb)l_3系は半導体もしくは絶縁体であった。AuとPbの価電子帯のエネルギー差が大きいためと考えられる。一方Cs(AuHg)l_3系では、電気伝導性の高い試料が得られたが、これも不安定な化合物である。Cs(Au_<0.5>Hg_<0.5>)l_3の電気伝導度を粉末加圧成形試料において測定したところ、250K付近で急激な抵抗の減少が見られた。現在詳細な解析が進行中である。
    (2)CsAgCl_3系の合成
    Agは4dが価電子帯のためAuよりもオンサイト‐クーロン反発が大きいため、混合原子価による格子歪みが小さいことが期待される。そこでCsAgCl_3の合成を試みた。まず、CslとAgClを電気炉で250℃に加熱してCsAgCl_2を合成した。これをドラフト内で塩素ガスにて酸化しCsAgCl_3を得た。X線粉末構造解析により、CsAuX_3系と同形であることがわかった。現在、本物質の物性測定と、これを母体とした物質開発が進行中である。
    (3)今後の課題
    六方アンビル型高圧発生装置を用いた高温高圧合成法も試みる予定である。この方法は酸化物高温超伝導体の合成で注目されており、高温高圧下で合成することにより、良質の単結晶を得ることができる。またこれにより、準安定相を常温常圧下で得ることも可能である。また申請者のこれまでの研究によっても明らかなように、金属ハロゲン化物結晶において圧力は極めて強い外部摂動効果として働く。高圧力は、結晶格子定数・エネルギーバンド構造・電子-電子間相互作用・電子-格子相互作用等を連続的に変化させることにより、固体物性を変えることが可能な手法である。上記の物質において高圧下での精度の高い測定を行ない、圧力印加による物性変化について電気的性質を中心に調べる予定である。また圧力効果の検討は、物質設計の指針を得るためにも重要である。

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  • 電子プロトン連動によるキャリヤ生成と新規電導機構

    Grant number:07232218  1995

    日本学術振興会  科学研究費助成事業  重点領域研究

    三谷 忠興, 安 正宣, 北川 宏, 岩佐 義宏

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    Grant amount:\1500000 ( Direct Cost: \1500000 )

    分子内および分子間水素結合を有する電荷移動型金属錯体:[Pd(H2DAG)(HDAG)] TCNQ(エチレンジアミノグリオキシム錯体)および[Pt(H2EDAG)(HEDAG)](ジアミノグリオキシム錯体)について、この錯体に特徴的な“金属-絶縁体相転移"に関する詳細な情報を得るを目的として以下のような研究を行った。
    1.オキシム系配位子は、酸‐塩基性を有する。そこで、エチレンジアミノグリオキシム錯体とTCNQの電荷移動錯体において、オキシムの酸‐塩基性を利用したTCNQのフィリング制御を試みた。電荷移動量ρ(TCNQ‐^ρ)が0.2、0.7、1.0(ラマン分光法により電荷移動量を評価した)の電荷移動錯体を作り分けることに成功した。
    2.これら錯体の単結晶を用いて、室温から極低温までの電気電導度・ESR・磁化率の研究を行ない、キャリヤ-の種類・濃度、伝導電子の散乱機構等の輸送現象について明らかにした。特に、カラム間水素が伝導電子を捕獲するという興味深い現象が観測された。
    3.同じ錯体の単結晶において、赤外から可視、紫外域にいたる偏光反射スペクトルを測定した。結果を解析し、それらの電子構造と電荷移動励起状態の性質を明かにした。また赤外吸収分光・ラマン分光により、電子‐プロトン結合に間するフォノンの興味ある知見を得た。
    4.上記の錯体の単結晶において高圧下の測定を行ない、圧力印加による物性変化について電気的性質と光学的性質を調べた。
    5.XPSの測定により、ベンゾキノンジオキシム錯体において、200K付近で中心金属から配位子へ電荷移動することがわかった。
    以上の測定から、この系での金属的挙動はこれまでにない金属状態であり、今後の研究の発展が期待される。

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  • BEDT-TTF系電荷移動錯体の合成とフィリング制御

    Grant number:07232101  1995

    日本学術振興会  科学研究費助成事業  重点領域研究

    岩佐 義宏, 長谷川 達生

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    Grant amount:\1700000 ( Direct Cost: \1700000 )

    われわれは、アクセプター性分子とBEDT-TTFとの組み合わせによって有機電荷移動錯体特有の物性発現を目的として、物質開発研究を行った。非常に多くのドナー、アクセプター分子を組み合わせて化合物を作製したが、本報告書では、カラム間コンタクトを作りやすいBEDT-TTFが、有機2成分の電荷移動錯体の構造、物性に顕著な影響を与えた新物質について報告する。
    1次元的な構造を有する従来型の有機2成分の電荷移動錯体は、低温で格子変形を起こしてパイエルス相に落ち込む。これは、分離積層(金属)、交互積層型(絶縁体)によらず、一次元系に非常に一般的に見られる傾向である。ところが、BEDT-TTFをドナーとする電荷移動錯体には、この一般的傾向からはずれた物質が数多く現れることが明らかになった。以下は従来の傾向からはずれる典型物質である。
    1.交互積層型反強磁性体(BEDT-TTF)(F2TCNQ)
    2.モット絶縁体(BEDT-TTF)(TCNQ)
    3.金属的錯体(BEDT-TTF)(XTCNQ)(X=F,Cl,Br)、(BEDT-TTF)(DCNQI誘導体)
    これらの、物質では帯磁率は低温に向かって上昇するか、ほとんど温度に依存しないパウリ常磁性を示す。特に、1.2.の絶縁体ではBEDT-TTF分子の横方向のつながりによって、かえってアクセプター分子が孤立した構造となり、その結果アクセプター分子上のスピンは低温までキュリー則に従う。このようにJの弱い局在スピンは1次元的構造をとりやすいドナーを選んだ場合にはほとんど見られない。以上述べたとおり、BEDT-TTF分子のカラム間結合を作りやすい性質は、伝導性物質だけでなく、絶縁性物質にも、反強磁性相を安定化させるような形で顕著に現れることが明らかになった。

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  • フラーレン化合物の高圧合成と物性研究

    Grant number:06224102  1994

    日本学術振興会  科学研究費助成事業  重点領域研究

    岩佐 義宏, 有馬 孝尚

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    Grant amount:\1900000 ( Direct Cost: \1900000 )

    C60及びそのアルカリ金属化合物に対する高圧効果および電子状態の研究を行い、以下の成果をあげた。
    1.C60ポリマーの高圧合成
    C60を5GPa、600℃以上の高温高圧下で処理すると、菱面体構造に変化し、それが常温常圧下で準安定に取り出せることを見出した。新しい相では、分子間距離が9.2Åまで縮み、分子の対称性が正二十面体対称性Ihよりも大きく低下していると、溶解度が大きく低下している。このことから菱面体相ではC60のポリマーができていること解釈された。その後ヨーロッパのグループによって、我々の見出した菱面体相はC60の2次元ポリマーであることが明らかにされた。本研究およびヨーロッパグループの研究によってC60ポリマーは新しい炭素の存在形態として確立した。
    2.C60アルカリ化合物における圧力誘起超伝導の探索
    C_<60>^<3->の状態を有するカルカリ化合物はほとんど超伝導性を示し、格子定数を大きくするとTcも上昇するという事実はよく知られている。ところが最近、格子定数を大きくしすぎると超伝導が消滅することがわかってきた。そこで、われわれはこのような非超伝導体(NH3K3C60,Cs3C60)に静水圧を印加することによってそれぞれTc=28K,40Kの超伝導が現れることを見出した。
    3.光学スペクトルによるC60アルカリ化合物の電子状態の研究
    AxC60(x=0,3,4,6)試料を共昇華法によって作製し、その光反射スペクトルを測定し、それから伝導度スペクトルを求めた。特にK4C60のスペクトルを初めて測定し、バンド描像に反してE=0.5eVに最低の吸収ピークをもつ半導体であることを明らかにした。

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  • 電子・プロトン連動によるキャリヤ生成と新規電導機構

    Grant number:06243214  1994

    日本学術振興会  科学研究費助成事業  重点領域研究

    三谷 忠興, 岩佐 義宏, 北川 宏

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    Grant amount:\2300000 ( Direct Cost: \2300000 )

    本年度は、電荷移動型金属錯体;[M(H2DAG)(HDAG)]・TCNQ(M=Ni,Pd,Pt)の磁性、光学スペクトル、ラマン散乱、X線解析、電導度、やその低温、高圧実験の基礎物性測定を行った。その結果、この物質が常温近傍で半導体一金属転移を示し、その要因が鎖間の水素結合の融解によることが判明した。このような相転移の観測ははじめてのものであり、世界的にも大いに注目されるものである。さらに、基礎物性の立場からこのシステムの物理的内容を明確にするために次のような実験を試た。
    1)光電子分光測定
    2)プロトンおよびH^-を用いた加速イオンビーム注入
    3)ab initio分子軌道法による光学スペクトルのシュミレーション
    1)の実験は、[M(H2DAG)(HDAG)]鎖におけるMのd電子とTCNQ鎖のπ電子のエネルギィー準位の相対的位置を決定する上で貴重な情報を与えるものであり、鎖間の電荷移動量などこの系の基本的物理量を決定する上で重要な鍵となる。本年度はその予備実験を行ったが、その結果、d電子とπ電子に関わる信号の検出に成功した。しかし、まだ電荷移動量との対応までには至っていない。
    2)のイオンビーム注入により物質変換の試みの実験は、今後の応用での新しい展開を計る上で重要である。予備実験においてイオン注入に成功した。プロトン注入により新たな水素結合が生成されたことは注目に値する。いま、その濃度と電気的挙動との相関関係を調べている。
    3)では、これまでに行った半経験的分子軌道計算のデータを基にして、厳密な分子軌道計算を行なった。その結果、上記の半導体一金属転移について理論的な裏付けを得ることができた。

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  • フラーレンとその化合物の単結晶作製と光物性

    Grant number:05233209  1993

    日本学術振興会  科学研究費助成事業  重点領域研究

    岩佐 義宏

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    Grant amount:\3000000 ( Direct Cost: \3000000 )

    本研究の目的は,フラーレン及びフラーレン化合物の単結晶ないしは良質試料を作製して主にその光学的性質を測定することによって,これらの物質の電子構造や電子格子相互作用を明らかにすることであった。本研究は,フラーレンにおける超伝導が,A_3C_<60>(A;アルカリ金属)などの特殊な組成(分子価数)のみで発現するのかという基本的な問題とも関連している。以下に本研究で得られた成果を列挙する。
    1.C_<60>,C_<70>単結晶を昇華法によって作製し,その光反射スペクトルを赤外〜真空紫外のエネルギー範囲で測定した。これにより、高エネルギースケールでの電子構造と光学定数を決定した。
    2.C_<60>,C_<70>薄膜の電場変調スペクトルを測定し,吸収端近傍の禁制遷移について詳細な知見を得た。3.C_<60>,C_<70>の単結晶及び溶液のT=2Kでのフォトルミネセンススペクトルの測定を行った。これは,光吸収によって生成された電子正孔対が固体および分子状態で受けるエネルギー緩和を敏感に反映するプローブである。溶媒によってmatrix-isolateされたC_<60>分子は比較的幅の広いエネルギー緩和の大きい発光スペクトルを示すが,C_<70>は幅の狭いエネルギー緩和の小さな発光スペクトルを示すことが明らかになった。この結果は,C_<60>分子の光励起状態と分子内振動の相互作用がC_<70>のそれに比べて異常に大きいことを示している。
    4.アルカリ金属C_<60>化合物A_χC_<60>の光スペクトルをA=K,Rb,χ=3,4,6について測定した。試料は,我々が独自に開発した共昇華法を用いて作製した。K_3C_<60>とRb_3C_<60>は,バンド描像から予測されるものに近いスペクトルを示したが,K_4C_<60>,Rb_4C_<60>は金属状態が予測されるにもかかわらず,0.4eVに吸収の山を有する半導体であることが明らかになった。

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  • 有機伝導体へのドーピング効果と金属-絶縁体転移

    Grant number:05640406  1993

    日本学術振興会  科学研究費助成事業  一般研究(C)

    岩佐 義宏

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    Grant amount:\2100000 ( Direct Cost: \2100000 )

    BEDT-TTF(ET)分子からなる二次元伝導層は,多くの有機超伝導体を与えることで有名である。本研究では,この伝導層のキャリア数を系統的に制御できる可能性を有する電荷移動錯体ET-TCNQを対象に金属絶縁体転移と絶縁体相の電子状態の解明を行い,以下の成果を得た。
    1.温度-圧力平面での電子相図の作成(電気抵抗測定)
    常圧で330Kに見られる金属絶縁体転移温度は12kbarの圧力を印加することにより約40Kまで降下した。しかしそれ以上の圧力を印加しても,転移温度は減少しなかった。電気抵抗の異方性が小さいため,伝導は主にET層によって担われている。すなわち,電子相図はET層に対応するものである。
    2.絶縁体相がモット絶縁体であることを見いだした。
    帯磁率,ESRの測定により,常圧での絶縁体相がモット絶縁体であることが明らかになった。TCNQ鎖はキュリー的な,また,ET層は温度依存性の弱い磁化率を示す。
    3.TCNQ鎖の反強磁性秩序化の発見
    T_c=3KでTCNQ一次元鎖が反強磁性に秩序化することを見いだした。従来,TCNQ鎖の低温基底状態はCDWやスピンパイエルス相などの非磁性相しか知られていなかった。TCNQの反強磁性転移の発見は本研究が初めてである。これは,二次元ET層を介した三次元的磁気的相互作用が比較的強いためと解釈されている。ET層の秩序化は明らかになっていないが,ESRの線幅がT〜35Kで急に広くなることから,この温度で反強磁性転移を示したと考えられる。

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  • 天然量子細線による励起子波動関数工学

    Grant number:03650005  1991

    日本学術振興会  科学研究費助成事業  一般研究(C)

    岩佐 義宏

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    Grant amount:\2000000 ( Direct Cost: \2000000 )

    半導体に微細加工を施すことによる電子の量子閉じ込め効果の研究がさかんに行なわれている。その対極にあるのが高分子を中心とした擬1次元物質であり、究極の量子細線あるいは天然の量子細線と呼ばれている。本研究では以上の観点から主に2つの物質群をとりあげ、これらの電子状態を非線形スペクトロスコピ-によって調べ1次元励起子固有の性質を明らかにした。本研究は半導体量子細線の研究とは相補的な情報を与えるとともに、高分子の非線形光学効果の解明に対し、重要な知見を与えた。これらは1次元励起子を使ったオプトエレクトロニクス“励起子工学"の重要な基礎となるものである。以下に具体的な成果を述べる。
    (1)ハロゲン架橋白金錯体は、白金がハロゲンを介して1次元的な配列をしている1次元物質である。この物質の配向薄膜を傾斜型キャスト法という方法ではじめて作製し、第3高調波発生法によって非線形光学スクぺクトルを測定した。レ-ザ-波長は2.2μmから0.5μmという広範囲に及んだ。これによって1次元的な電荷移動励起子(特に通常の線形分光では見えない禁制の励起子)が非線形光学応答に重要な寄与をしていることを示した。
    (2)ポリシランとはシリコン原子が1次元的につながったシリコンポリマ-である。この物質の薄膜を作製し、第3高調波発生法によって非線形光学応答を測定した。これによって線形応答では見ることのできない共鳴構造を見出し、ポリシランの励起状態が1次元ワニエ励起子モデルで記述できることを見出した。
    (3)これらの実験結果と炭素系高分子の非線形応答のデ-タを整理し、1次元励起子モデルによって統一的に理解できることを示した。

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  • Properties and functions of Fullerenes and carbon nanotubes

    1990

    JST Basic Research Programs (Core Research for Evolutional Science and Technology :CREST) 

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    Grant type:Competitive

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  • フラーレン/カーボンナノチューブの物性と機能の研究

    1990

    JST戦略的創造研究推進制度(研究チーム型) (戦略的基礎研究推進事業:CREST) 

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    Grant type:Competitive

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  • Nonlinear Optical Properties of Organic Polymer Films

    Grant number:01420016  1989 - 1992

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for General Scientific Research (A)

    KODA Takao, TOMIOKA Akihiro, MIYANO Kenjiro, HASEGAWA Tatsuo, IWASA Yoshihiro

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    Grant amount:\16700000 ( Direct Cost: \16700000 )

    At the first stage of this research project,we have focused our attention on the pi-conjugated polymer,polydiacetylenes. We established the fabrication technique of highly-oriented polydiacetylene films by vacuum deposition in 1987 [1],and extensively investigated the third- order nonlinear optical (NLO) properties of thus obtained films [1-4,10].
    In the meantime, we developed the simple and accurate method for determining the third-order NLO susceptibility of thin films [6,7].
    The research objects were extended to other polymers and low dimensional organic molecular crystals. The NLO properties of quasi- one-dimensional platinum compounds [5,8] and copper phthalocyanine [9] have been clarified.
    The most important results were obtained for o-conjugated silicon polymer,polysilanes [11-14]. The modulus and phase of the complex third-order NLO susceptibility spectra were measured on the polysilane films over a wide photon energy range. From the analysis of the experimental results in terms of the one-dimensional exciton model, the important aspects of NLO processes of polysilanes are elucidated.
    These researches were summarized in [15].

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  • Raman scattering study on organic semiconductors having gigantic dielectric constant

    Grant number:01550007  1989 - 1990

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for General Scientific Research (C)

    IWASA Yoshihiro

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    Grant amount:\2400000 ( Direct Cost: \2400000 )

    Mixed stack organic semiconductors, composed of oneーdimensional chains of alternately stacked donor and acceptor molecules have an instability to molecular valence change. These materials show anomalous response to the electric field. One is a gigantic dielectric response and the other is a current switching effect. Especially, the latter has been attracted much attention in this decade due to possible application to molecular electronics. We have investigated the transport, dielectric, and optical properties of these materials. Raman and infrared spectra were measured to investigate the microscopic properties of the switch-on state.
    From the experimental results, we have concluded that the stacking fault on the one-dimensional chain (in other words, solitons) play important roles in the dynamical properties of these compounds. The ionic charge transfer compounds undergo a structural phase transition. The switching effect was found to occur conspicuously in the low temperature phase, where neighboring molecules are dimerized. It was found that this dimerization order is partially broken by too much current mediated by solitonic charge carriers.

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  • IIA-VIB族化合物半導体の発光機構とその動特性

    Grant number:62604526  1987

    日本学術振興会  科学研究費助成事業  重点領域研究

    国府田 隆夫, 江良 晧, 石川 謙, 岩佐 義宏

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    Grant amount:\2800000 ( Direct Cost: \2800000 )

    本研究の目的は, 最近本研究者らが組織的に進めてきた各種のIIA-VIB族化合物の単結晶作製と, これについて得られた基礎的物性に関する研究を基盤として, これらの化合物結晶が示す特徴的な発光(ルミネセンス)の微視的機構を解明することにある. この目的に沿って, 本年度はこれまでの測定によって得られた各種の分光スペクトル(反射, 吸収, 発光, 発光励起)の実験データと理論的研究の結果を解析して, 各結晶の電子エネルギー帯構造を解明し, ついで各種の不純物や格子欠陥を介した電子-正孔対の再結合過程を調べた. 特に, 大部分のIIA〜VIB族化合物結晶で予想されている禁制間接遷移という特異な性質が, その発光特性にどのように反映されているかを実験的に明らかにすることを主要な目的として研究を進めた.
    IIA-VIB族化合物結晶は, BaOを唯一の例外として, すべてΓ点の価電子帯頂点とX点の電動帯底点の間に間接型のバンド間隙をもっている. 吸収, 発光スペクトル, 発光励起スペクトル, APW法による理論的バンド計算によって, このことが確かめられた. 結晶中に励起された電子, 正孔対は, このようなバンド構造により格子フォノンを放出して直接的に再結合することが禁制されている. 有効な再結合中心が存在すれば, それを介して効率の高いルミネッセンスが生じると予想されるが, 実際に等電子配置不純物や希土類イオン不純物によって生じる発光には, そのような特徴が認められる. 結晶中に励起された電子-正孔対が, どのような過程をたどって特定の発光中心での再結合発光遷移に到るかを明らかにするために, 電子軌道放射光を利用した広い波長領域の発光励起スペクトルの測定と, 単バンチモードによるパルス光で励起された発光の減衰特性を詳しく調べ, 新しい知見を得た.

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  • Development of Optical Memory Recording Films using Conjugated Polymers of Polydiacetylenes

    Grant number:61850002  1986 - 1988

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Developmental Scientific Research

    KODA Takao, ISHIKAWA Ken, IWASA Yoshihiro

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    Grant amount:\9800000 ( Direct Cost: \9800000 )

    The aim of present project is to explore possibility of utilizing the photo-induced isomerization of the conjugated polymers, in the form of thin films, as a fast and high density optical information recording. For this purpose, we have chosen specific class of conjugated polymers, polydiacetylenes, which are obtained by the solid state polymerization from diacetylene monomers, RC=C-C=CR, wher R stands for the suitable sudstitutional side group. A remarkable feature of these polymers is that their chemical and physical properties can be varied to a large extent by modifying the structure of R. Making use of this advantage, we were able to prepare fairly good thin films of polydiacetylenes by means of conventional vacuum deposition method. As compared with previous film fabrication technigues, the present method is more suitable for the application to optical recording devices, for the simplicity, the film guality , as well as the feasibility of preferential alignment of polymers in the film. Various optical properties of these vacuum deposited films have been characterized. An important finding is the possibility of sensitization of photochromism in the near infrared region by the photo-induced electron injection from an organic dye layer, such as phthalocyanine film, to the polydiacetylene films. It has been proved by this study that polydiacetylene films are useful for high speed ( with the response time of a few nsecond) and high resolution optical recording material for the near infrared light obtained from a conventional semiconductor laser.

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  • Solid State Properties of Organic Materials

    1986

    JST Basic Research Programs (Core Research for Evolutional Science and Technology :CREST) 

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    Grant type:Competitive

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  • 有機結晶・デバイスの物性

    1986

    JST戦略的創造研究推進制度(研究チーム型) (戦略的基礎研究推進事業:CREST) 

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    Grant type:Competitive

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