Updated on 2025/09/30

写真a

 
hanzawa kota
 
Organization
Institute of Integrated Research Materials and Structures Laboratory Assistant Professor
Title
Assistant Professor
External link

Degree

  • 博士（工学） ( 2019.3 )

Research Interests

  • 半導体

  • 超伝導体

Research Areas

  • Nanotechnology/Materials / Inorganic materials and properties

Papers

  • Realization of Non‐Equilibrium Wurtzite Structure in Heterovalent Ternary MgSiN2 Film Grown by Reactive Sputtering

    Sotaro Kageyama, Kazuki Okamoto, Shinnosuke Yasuoka, Keisuke Ide, Kota Hanzawa, Yoshiomi Hiranaga, Pochun Hsieh, Sankalpa Hazra, Albert Suceava, Akash Saha, Hiroko Yokota, Kei Shigematsu, Masaki Azuma, Venkatraman Gopalan, Hiroshi Uchida, Hidenori Hiramatsu, Hiroshi Funakubo

    Advanced Electronic Materials   2025.6

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    Publishing type：Research paper (scientific journal)  

    DOI： 10.1002/aelm.202400880

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  • Theoretical and data-driven approaches to semiconductors and dielectrics: from prediction to experiment

    Fumiyasu Oba, Takayuki Nagai, Ryoji Katsube, Yasuhide Mochizuki, Masatake Tsuji, Guillaume Deffrennes, Kota Hanzawa, Akitoshi Nakano, Akira Takahashi, Kei Terayama, Ryo Tamura, Hidenori Hiramatsu, Yoshitaro Nose, Hiroki Taniguchi

    Science and Technology of Advanced Materials   2024.12

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    Publishing type：Research paper (scientific journal)  

    DOI： 10.1080/14686996.2024.2423600

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  • Quadrupling the depairing current density in the iron-based superconductor SmFeAsO1–xHx

    Masashi Miura, Serena Eley, Kazumasa Iida, Kota Hanzawa, Jumpei Matsumoto, Hidenori Hiramatsu, Yuki Ogimoto, Takumi Suzuki, Tomoki Kobayashi, Toshinori Ozaki, Hodaka Kurokawa, Naoto Sekiya, Ryuji Yoshida, Takeharu Kato, Tatsunori Okada, Hiroyuki Okazaki, Tetsuya Yamaki, Jens Hänisch, Satoshi Awaji, Atsutaka Maeda, Boris Maiorov, Hideo Hosono

    Nature Materials   2024.10

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

    <jats:title>Abstract</jats:title><jats:p>Iron-based 1111-type superconductors display high critical temperatures and relatively high critical current densities <jats:italic>J</jats:italic><jats:sub>c</jats:sub>. The typical approach to increasing <jats:italic>J</jats:italic><jats:sub>c</jats:sub> is to introduce defects to control dissipative vortex motion. However, when optimized, this approach is theoretically predicted to be limited to achieving a maximum <jats:italic>J</jats:italic><jats:sub>c</jats:sub> of only ∼30% of the depairing current density <jats:italic>J</jats:italic><jats:sub>d</jats:sub>, which depends on the coherence length and the penetration depth. Here we dramatically boost <jats:italic>J</jats:italic><jats:sub>c</jats:sub> in SmFeAsO<jats:sub>1–<jats:italic>x</jats:italic></jats:sub>H<jats:sub><jats:italic>x</jats:italic></jats:sub> films using a thermodynamic approach aimed at increasing <jats:italic>J</jats:italic><jats:sub>d</jats:sub> and incorporating vortex pinning centres. Specifically, we reduce the penetration depth, coherence length and critical field anisotropy by increasing the carrier density through high electron doping using H substitution. Remarkably, the quadrupled <jats:italic>J</jats:italic><jats:sub>d</jats:sub> reaches 415 MA cm<jats:sup>–2</jats:sup>, a value comparable to cuprates. Finally, by introducing defects using proton irradiation, we obtain high <jats:italic>J</jats:italic><jats:sub>c</jats:sub> values in fields up to 25 T. We apply this method to other iron-based superconductors and achieve a similar enhancement of current densities.</jats:p>

    DOI： 10.1038/s41563-024-01952-7

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  • Wide-Gap p-Type Layered Oxychalcogenides AE2CuInO3Ch (AE: Alkaline Earth; Ch: Chalcogen): Unusually Low Residual Carrier Concentration and Green-to-Red Emission

    Xinyi He, Tatsuya Cho, Takayoshi Katase, Kota Hanzawa, Suguru Kitani, Hidenori Hiramatsu, Hideo Hosono, Toshio Kamiya

    Chemistry of Materials   36 ( 12 )   2024.6

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

    DOI： 10.1021/acs.chemmater.4c00724

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  • Phonon drag thermopower persisting over 200 K in FeSb2 thin film on SrTiO3 single crystal

    Chihiro Yamamoto, Xinyi He, Kota Hanzawa, Takayoshi Katase, Masato Sasase, Jun-ichi Yamaura, Hidenori Hiramatsu, Hideo Hosono, Toshio Kamiya

    Applied Physics Letters   2024.5

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

    <jats:p>FeSb2 is known as a potential low-temperature thermoelectric material with the record-high power factor (PF) originating from the huge phonon drag thermopower (Sg). However, the Sg contribution to PF has been observed only at very low temperatures (T) &amp;lt; 40 K. In this paper, we found that the Sg persists at much higher T up to 240 K and enhances PF in FeSb2 thin films deposited on SrTiO3 single crystals. The FeSb2 films showed phonon drag Sg peak at T ∼ 60 K, and the Sg peak value was largely enhanced from 56 to 208 μV/K by varying film thicknesses from 10 to 100 nm. Due to thickness-dependent Sg contribution, the maximum PF = 31.3 μW/(cm K2) was obtained for a 37-nm thick film. In addition, the onset temperature, where Sg starts to appear, can be largely increased due presumably to the enhanced electron–phonon interaction by phonon leakage from the SrTiO3 substrate to the thin FeSb2 layer. Heterostructuring with an oxide would be an effective approach to enhance the phonon drag effect to increase PF in higher T regions for future thermoelectric cooling and energy conversion devices.</jats:p>

    DOI： 10.1063/5.0204885

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  • Carrier generation and compensation mechanism in La2SnO2S3

    Teruya Nagafuji, Koshiro Osuna, Kota Hanzawa, Tomoya Gake, Soungmin Bae, Zhongxu Hu, Takayoshi Katase, Akira Takahashi, Hidenori Hiramatsu, Fumiyasu Oba

    Journal of Materials Chemistry C   2024

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

    DOI： 10.1039/d4tc01116c

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  • Enhancing analysis efficiency: Automation of spectroscopic ellipsometry for crystalline semiconductors and transparent conductive oxides

    Sara Maeda, Yusuke Tani, Hirotaka Katayama, Daiji Kanematsu, Kohei Oiwake, Yukinori Nishigaki, Tetsuhiko Miyadera, Masayuki Chikamatsu, Takayuki Nagai, Takuma Aizawa, Kota Hanzawa, Hidenori Hiramatsu, Akira Terakawa, Hideo Hosono, Hiroyuki Fujiwara

    Thin Solid Films   787   140099 - 140099   2023.12

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

    DOI： 10.1016/j.tsf.2023.140099

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  • Effect of iron substitution on electronic conductivity of bismuth sesquioxide glasses

    Kazuki Mitsui, Zhongxu Hu, Kota Hanzawa, Takayoshi Katase, Hidenori Hiramatsu, Akira Saitoh

    Journal of Applied Physics   2023.8

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

    <jats:p>Several glassy oxide semiconductors exhibit large electron mobilities; however, these oxides may not be considered environmentally friendly because of their toxicity. Herein, we report on the electrical conduction of iron oxide-containing bismuth sesquioxide borate glasses that are not toxic and show ohmic transport in the temperature range of 100–400 °C. The dominant carrier is the electron, which is revealed by the signs of Hall and Seebeck coefficients, without sign anomalies. The Hall mobility is ∼0.1 cm2/(V s), and the carrier density is ∼6 × 1015 cm−3 at 400 °C. The Seebeck coefficient is approximately −500 μV/K at 388 °C. The carriers might be generated by charge transfer between Fe2+ and Fe3+ substituted in the glass, and they exhibit thermally activated hopping-type electronic conduction. The oxide glass can be used as a glass thermistor for a temperature range of 100–400 °C.</jats:p>

    DOI： 10.1063/5.0149523

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  • Heteroepitaxial Growth, Degenerate State, and Superconductivity of Perovskite-Type LaWN3 Thin Films

    Kota Hanzawa, Hidenori Hiramatsu

    ACS Applied Electronic Materials   5 ( 5 )   2023.5

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

    DOI： 10.1021/acsaelm.3c00249

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  • High upper critical field (120 T) with small anisotropy of highly hydrogen-substituted SmFeAsO epitaxial film

    Kota Hanzawa, Jumpei Matsumoto, Soshi Iimura, Yoshimitsu Kohama, Hidenori Hiramatsu, Hideo Hosono

    Physical Review Materials   6 ( 11 )   2022.11

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    Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

    DOI： 10.1103/physrevmaterials.6.l111801

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  • High pressure synthesis, physical properties and electronic structure of monovalent iron compound LaFePH

    Soshi Iimura, Takashi Sasaki, Kota Hanzawa, Satoru Matsuishi, Hideo Hosono

    Journal of Solid State Chemistry   2022.11

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

    DOI： 10.1016/j.jssc.2022.123546

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  • Electronic and Lattice Thermal Conductivity Switching by 3D−2D Crystal Structure Transition in Nonequilibrium (Pb1−xSnx)Se

    Yusaku Nishimura, Xinyi He, Takayoshi Katase, Terumasa Tadano, Keisuke Ide, Suguru Kitani, Kota Hanzawa, Shigenori Ueda, Hidenori Hiramatsu, Hitoshi Kawaji, Hideo Hosono, Toshio Kamiya

    Advanced Electronic Materials   2022.9

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    <jats:title>Abstract</jats:title><jats:p>Dynamic control of thermal transport in solid materials is highly desired for thermal management technology. However, the development of a material exhibiting large modulation of thermal conductivity (κ) by external stimuli remains a major challenge. Here, the large κ modulation is reported by the reversible 3D to 2D crystal structure transition in a nonequilibrium solid solution of (Pb<jats:sub>1−</jats:sub><jats:italic><jats:sub>x</jats:sub></jats:italic>Sn<jats:italic><jats:sub>x</jats:sub></jats:italic>)Se, where Pb<jats:sup>2+</jats:sup> stabilizes a 3D cubic structure while Sn<jats:sup>2+</jats:sup> does a 2D layered structure. The phase boundary of these phases is induced in (Pb<jats:sub>0.5</jats:sub>Sn<jats:sub>0.5</jats:sub>)Se bulk polycrystals by thermally quenching the high‐temperature solid solution phase. Through the 3D–2D phase transition, the 1/2.9‐times decrease of lattice κ (κ<jats:sub>lat.</jats:sub>) is achieved by strong phonon scattering in the 2D layered structure, and the electronic κ (κ<jats:sub>ele.</jats:sub>) is also decreased by 5 orders of magnitude due to the electronic phase transition from a 3D high conductivity state to a 2D semiconducting state. The total κ (<jats:bold>=</jats:bold>κ<jats:sub>lat.</jats:sub> <jats:bold>+</jats:bold> κ<jats:sub>ele.</jats:sub>) modulation ratio κ<jats:sub>3D phase</jats:sub>/κ<jats:sub>2D phase</jats:sub> <jats:bold>=</jats:bold> 3.6 is attained at 373 K. The present strategy will lead to a novel concept for designing thermal management materials through crystal‐structure dimensionality switch using nonequilibrium phase boundaries.</jats:p>

    DOI： 10.1002/aelm.202200024

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  • Low Residual Carrier Density and High In-Grain Mobility in Polycrystalline Zn3N2 Films on a Glass Substrate

    Kaiwen Li, Atsushi Shimizu, Xinyi He, Keisuke Ide, Kota Hanzawa, Kosuke Matsuzaki, Takayoshi Katase, Hidenori Hiramatsu, Hideo Hosono, Qun Zhang, Toshio Kamiya

    ACS Applied Electronic Materials   4 ( 4 )   2022.4

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

    DOI： 10.1021/acsaelm.2c00181

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  • Origins of the coloration from structure and valence state of bismuth oxide glasses

    Akira Saitoh, Katsuki Hayashi, Kota Hanzawa, Shigenori UEDA, Shiro Kawachi, Jun-ichi Yamaura, Keisuke Ide, Junghwan Kim, Grégory Tricot, Satoru Matsuishi, Kazuki Mitsui, Tatsuki Shimizu, Masami Mori, Hideo Hosono, Hidenori Hiramatsu

    Journal of Non-Crystalline Solids   2021.5

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

    DOI： 10.1016/j.jnoncrysol.2021.120720

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  • Extraordinary Strong Band‐Edge Absorption in Distorted Chalcogenide Perovskites

    Yukinori Nishigaki, Takayuki Nagai, Mitsutoshi Nishiwaki, Takuma Aizawa, Masayuki Kozawa, Kota Hanzawa, Yoshitsune Kato, Hitoshi Sai, Hidenori Hiramatsu, Hideo Hosono, Hiroyuki Fujiwara

    Solar RRL   2020.5

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

    <jats:sec><jats:label /><jats:p>All existing solar cell materials including hybrid perovskites show rather small absorption coefficient (<jats:italic>α</jats:italic>) of ≈10<jats:sup>4</jats:sup> cm<jats:sup>−1</jats:sup> in the bandgap (<jats:italic>E</jats:italic><jats:sub>g</jats:sub>) transition region. The weak band‐edge light absorption is an essential problem, limiting conversion efficiency particularly in a tandem solar cell. Herein, all distorted chalcogenide perovskites (BaZrS<jats:sub>3</jats:sub>, SrZrS<jats:sub>3</jats:sub>, BaHfS<jats:sub>3</jats:sub>, and SrHfS<jats:sub>3</jats:sub>) are found experimentally to exhibit extraordinary high <jats:italic>α</jats:italic> exceeding 10<jats:sup>5</jats:sup> cm<jats:sup>−1</jats:sup> near <jats:italic>E</jats:italic><jats:sub>g</jats:sub>, indicating the highest band‐edge <jats:italic>α</jats:italic> among all known solar cell materials. The giant absorption in the <jats:italic>E</jats:italic><jats:sub>g</jats:sub> region, which is consistent with the first principles, arises from the intense p–d interband transition enabled by dense S 3p valence states. For solar cell application, low‐gap BaZrS<jats:sub>3</jats:sub> derivatives, Ba(Zr,Ti)S<jats:sub>3</jats:sub> and BaZr(S,Se)<jats:sub>3</jats:sub>, are further synthesized. Among the possible candidates of top‐cell materials, an earth‐abundant and nontoxic Ba(Zr,Ti)S<jats:sub>3</jats:sub> alloy shows great potential, reaching a maximum potential efficiency exceeding 38% in a chalcogenide perovskite/crystalline Si tandem architecture.</jats:p></jats:sec>

    DOI： 10.1002/solr.201900555

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  • Superconductivity at 48 K of heavily hydrogen-doped SmFeAsO epitaxial films grown by topotactic chemical reaction using CaH2

    Jumpei Matsumoto, Kota Hanzawa, Masato Sasase, Silvia Haindl, Takayoshi Katase, Hidenori Hiramatsu, Hideo Hosono

    Physical Review Materials   2019.10

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

    DOI： 10.1103/physrevmaterials.3.103401

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  • Particulate Generation on Surface of Iron Selenide Films by Air Exposure

    Hidenori Hiramatsu, Kota Hanzawa, Toshio Kamiya, Hideo Hosono

    Journal of Superconductivity and Novel Magnetism   2019.10

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

    DOI： 10.1007/s10948-019-5020-9

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  • Heteroepitaxial Thin-Film Growth of a Ternary Nitride Semiconductor CaZn2N2

    Masatake Tsuji, Kota Hanzawa, Hiroyuki Kinjo, Hidenori Hiramatsu, Hideo Hosono

    ACS Applied Electronic Materials   1 ( 8 )   2019.7

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

    DOI： 10.1021/acsaelm.9b00248

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  • Stabilization and heteroepitaxial growth of metastable tetragonal FeS thin films by pulsed laser deposition

    Kota Hanzawa, Masato Sasase, Hidenori Hiramatsu, Hideo Hosono

    Superconductor Science and Technology   2019.5

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    Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1361-6668/ab097e

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  • Material Design of Green-Light-Emitting Semiconductors: Perovskite-Type Sulfide SrHfS3

    Kota Hanzawa, Soshi Iimura, Hidenori Hiramatsu, Hideo Hosono

    Journal of the American Chemical Society   141 ( 13 )   2019.3

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

    DOI： 10.1021/jacs.8b13622

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  • Insulator-like behavior coexisting with metallic electronic structure in strained FeSe thin films grown by molecular beam epitaxy

    Kota Hanzawa, Yuta Yamaguchi, Yukiko Obata, Satoru Matsuishi, Hidenori Hiramatsu, Toshio Kamiya, Hideo Hosono

    Physical Review B   2019.1

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

    DOI： 10.1103/physrevb.99.035148

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  • Pulsed laser deposition of SmFeAsO1− on MgO(100) substrates

    Silvia Haindl, Hiroyuki Kinjo, Kota Hanzawa, Hidenori Hiramatsu, Hideo Hosono

    Applied Surface Science   2018.4

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

    DOI： 10.1016/j.apsusc.2017.08.061

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  • Role of fluorine in two-dimensional dichalcogenide of SnSe 2

    Jin Tae Kim, Da Seul Hyeon, Kota Hanzawa, Ayaka Kanai, Se Yun Kim, Yong Jei Lee, Hideo Hosono, Joonho Bang, Kimoon Lee

    Scientific Reports   2018.1

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

    <jats:title>Abstract</jats:title><jats:p>Authors report an effect of F substitution on layered SnSe<jats:sub>2</jats:sub> through the successful synthesis of polycrystalline SnSe<jats:sub>2<jats:bold><jats:italic>−</jats:italic></jats:bold><jats:italic>δ</jats:italic></jats:sub>F<jats:sub>
    <jats:italic>x</jats:italic>
    </jats:sub> (0.000 ≤ <jats:italic>x</jats:italic> ≤ 0.010) by solid-state reaction. Accompanied with density functional theory calculations, the blue shift of A<jats:sub>1g</jats:sub> peak in Raman spectra reveal that F<jats:sup>−</jats:sup> ions are substituted at Se vacancy sites as decreasing the reduced mass of vibrational mode associated with Sn–Se bonding. From the measurements of electrical parameters, conductivity as well as carrier concentration are governed by thermally activated behavior, while such behavior is suppressed in Hall mobility, which occurs as F ratio increases. Based on Arrhenius relation, it is found that the potential barrier height at the grain boundary is suppressed with increasing F amount, suggesting that the F<jats:sup>−</jats:sup> ion is a promising candidate for the grain boundary passivation in the two-dimensional dichalcogenide system.</jats:p>

    DOI： 10.1038/s41598-018-20111-y

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  • Exploration of Stable Strontium Phosphide-Based Electrides: Theoretical Structure Prediction and Experimental Validation

    Junjie Wang, Kota Hanzawa, Hidenori Hiramatsu, Junghwan Kim, Naoto UMEZAWA, Koki Iwanaka, Tomofumi Tada, Hideo Hosono

    Journal of the American Chemical Society   2017.11

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

    DOI： 10.1021/jacs.7b06279

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  • Key Factors for Insulator–Superconductor Transition in FeSe Thin Films by Electric Field

    Kota Hanzawa, Hikaru Sato, Hidenori Hiramatsu, Toshio Kamiya, Hideo Hosono

    IEEE Transactions on Applied Superconductivity   2017.6

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    Publishing type：Research paper (scientific journal)  

    DOI： 10.1109/tasc.2016.2639738

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  • In-situ growth of superconducting SmO1−xFxFeAs thin films by pulsed laser deposition

    Silvia Haindl, Kota Hanzawa, Hikaru Sato, Hidenori Hiramatsu, Hideo Hosono

    Scientific Reports   2016.10

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    <jats:title>Abstract</jats:title><jats:p>Oxypnictide thin film growth by pulsed laser deposition (PLD) is one of many insufficiently resolved issues in the research of iron-based superconductors. Here we report on the successful realization of superconducting SmO<jats:sub>1−<jats:italic>x</jats:italic></jats:sub>F<jats:sub><jats:italic>x</jats:italic></jats:sub>FeAs oxypnictide thin film growth by <jats:italic>in-situ</jats:italic> PLD on CaF<jats:sub>2</jats:sub> (fluorite) substrates. CaF<jats:sub>2</jats:sub> acts as fluorine supplier by diffusion and thus enables superconducting oxypnictide thin film growth by PLD. Films are grown heteroepitaxially and characteristically have a broad resistive normal-to-superconducting transition. Best films have onset transition temperatures around 40 K. The proposed <jats:italic>in-situ</jats:italic> PLD film growth offers an alternative and cheap route for the fabrication of iron oxypnictides. PLD becomes now an additional option for iron oxypnictide synthesis.</jats:p>

    DOI： 10.1038/srep35797

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  • Electric field-induced superconducting transition of insulating FeSe thin film at 35 K

    Kota Hanzawa, Hikaru Sato, Hidenori Hiramatsu, Toshio Kamiya, Hideo Hosono

    Proceedings of the National Academy of Sciences   2016.4

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    <jats:title>Significance</jats:title>
    <jats:p>
    One of the key strategies for obtaining higher superconducting critical temperature (
    <jats:italic>T</jats:italic>
    <jats:sub>c</jats:sub>
    ) is to dope carriers into an insulator parent material with strong electron correlation. Here, we examined electrostatic carrier doping to insulator-like thin (∼10-nm-thick) FeSe epitaxial films using an electric double-layer transistor (EDLT) structure. The maximum
    <jats:italic>T</jats:italic>
    <jats:sub>c</jats:sub>
    obtained is 35 K, which is 4× higher than that of bulk FeSe. This result demonstrates that EDLTs are useful tools to explore the ultimate
    <jats:italic>T</jats:italic>
    <jats:sub>c</jats:sub>
    for insulating parent materials, and opens a way to explore high-
    <jats:italic>T</jats:italic>
    <jats:sub>c</jats:sub>
    superconductivity, where carrier doping is difficult by conventional chemical substitution.
    </jats:p>

    DOI： 10.1073/pnas.1520810113

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Presentations

  • スピネル型硫化物へのキャリアドーピングと電子輸送特性評価

    長澤遼河, 半沢幸太, 平松秀典

    第63回セラミックス基礎科学討論会  2025.1 

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    Language：Japanese   Presentation type：Oral presentation (general)  

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  • 3元系硫化物への キャリア ドーピングと光機能制御 Invited

    半沢 幸太, 永井 隆之, 平松 秀典, 細野 秀雄

    第72回応用物理学会春季学術講演会  2025.3 

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    Language：Japanese   Presentation type：Oral presentation (invited, special)  

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  • Analyses of Upper Critical Field for H-Substituted SmFeAsO Epitaxial Films Based on Single- and Multi-Band Theoretical Models

    Kota Hanzawa, Masashi Miura, Jumpei Matsumoto, Hidenori Hiramatsu, Hideo Hosono

    Iron-based Superconductors:Advances towards applications 2025 (IBS2app 2025)  2025.2 

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    Language：English   Presentation type：Poster presentation  

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  • Highly Hydrogen-Substituted 1111-Type SmFeAsO Epitaxial Films: Fabrication and Superconducting Properties Invited

    Kota Hanzawa, Hidenori Hiramatsu, Hideo Hosono

    2023.5 

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  • 実験的に決定した水素置換型鉄系超伝導体SmFeAsOの上部臨界磁場と磁気異方性

    半沢 幸太, 松本 惇平, 飯村 壮史, 小濱 芳允, 平松 秀典, 細野 秀雄

    第70回応用物理学会春季学術講演会  2023.3 

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  • Superconductivity of Iron-Based Superconductor Films Heavily Doped by Hydrogen Invited

    2023.12 

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  • Optoelectronic properties of Magnesium Selenide Epitaxial Films

    Kohei Yamashita, Kota Hanzawa, Shigenori Ueda, Kazuki Kaneko, Ryuichiro Hashimoto, Tomoya Gake, Akira Takahashi, Fumiyasu Oba, Hidenori Hiramatsu

    2024.10 

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  • Heteroepitaxial Growth of a Perovskite Type Nitride

    Kota Hanzawa, Hidenori Hiramatsu

    2024.2 

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  • 立方晶パイロクロア型Ca2Ta2O7の高圧合成

    福永 朋孝, 半沢幸太, 平松秀典

    第63回セラミックス基礎科学討論会  2025.1 

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  • p-Type Carrier Doping of a Wide Gap Binary Chalcogenide, MgSe

    山下 耕平, 半沢 幸太, 上田 茂典, 金子 和樹, 橋本 龍一郎, 我毛 智哉, 高橋 亮, 大場 史康, 平松 秀典

    日本MRS年次大会  2024.12 

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    Language：Japanese   Presentation type：Oral presentation (general)  

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  • ペロブスカイト型LaWN 3 エピタキシャル薄膜の光電子物性

    半沢幸太, 平松秀典

    第63回セラミックス基礎科学討論会  2025.1 

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  • ワイドギャップMgSeエピタキシャル薄膜へのp型ドーピング

    山下 耕平, 半沢 幸太, 上田 茂典, 金子 和樹, 橋本 龍一郎, 我毛 智哉, 高橋 亮, 大場 史康, 平松 秀典

    第63回セラミックス基礎科学討論会  2025.1 

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Research Projects

  • トポタクティック反応を用いた水素ドープ1111型鉄系超伝導体薄膜の電子状態解析

    Grant number：22K14601  2022.4 - 2025.3

    日本学術振興会  科学研究費助成事業  若手研究

    半沢 幸太

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    Grant amount：\4550000 （ Direct Cost: \3500000 、 Indirect Cost：\1050000 ）

    鉄系超伝導体の中で最も高い超伝導臨界温度を有する1111型LnFeAsO（Ln = 希土類金属）はフッ素や水素をドープすることで超伝導を発現する。特に、水素を用いた場合は水素濃度に対する超伝導相図が特異なふるまいを示すことが知られており、超伝導発現起源に迫る上で、水素ドープ1111の物性や電子構造解明は重要な課題である。そのため本研究課題では、水素ドープSmFeAsOエピタキシャル薄膜の基礎物性評価と電子状態評価に取り組んできた。130Tの強磁場下で水素ドープSmFeAsOエピタキシャル薄膜の上部臨界磁場を評価した結果、SmFeAsOが鉄系超伝導体において実測値としては最大の120Tの上部臨界磁場を有することを明らかにし、上部臨界磁場の温度依存性を評価することでこの物質の超伝導対破壊の起源に迫る知見を得た。より詳細な解析を行うためには、様々な水素濃度の試料を比較する必要があるが、現在用いているプロセスでは水素濃度の制御が難しかった。そのため、水素濃度を制御可能なプロセスの開拓を試みた。

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  • Development of efficient green-light emitting diode based on band folding

    Grant number：20K15170  2020.4 - 2024.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Early-Career Scientists

    Hanzawa Kota

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    Grant amount：\4160000 （ Direct Cost: \3200000 、 Indirect Cost：\960000 ）

    In this research project, we focused on non-oxide compounds with distorted perovskite-type structures owing to their superior electronic structures such as band folding for optoelectronic property and aimed to develop highly-efficient optical semiconductor devices. To realize the efficient device properties, it is essential to fabricate the high quality epitaxial thin films. For sulfide semiconductor SrHfS3 with outstanding optoelectronic characteristics and nitride compound LaWN3, which is a candidate of novel ferroelectric semiconductor, we developed the epitaxial thin-film growth processes and consequently succeeded in fabrications of the epitaxial films by pulsed laser deposition and magnetron sputtering techniques.

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