Updated on 2022/06/07

写真a

 
AKIBA Kazuto
 
Organization
Faculty of Natural Science and Technology Assistant Professor
Position
Assistant Professor
External link

Degree

  • 博士(理学) ( 2018.3   東京大学 )

Research Interests

  • Fermi Surface

  • Magneto-transport Properties

  • Semimetal

  • Low Temperature

  • Topological Electronic Phase

  • Quantum Oscillation

  • Material Properties in Extreme Conditions

  • High Magnetic Field

  • High Pressure

Research Areas

  • Natural Science / Magnetism, superconductivity and strongly correlated systems

Education

  • The University of Tokyo   理学系研究科   物理学専攻 博士課程

    2015.4 - 2018.3

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    Country: Japan

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  • The University of Tokyo   理学系研究科   物理学専攻 修士課程

    2013.4 - 2015.3

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    Country: Japan

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  • Nagoya University   理学部   物理学科

    2009.4 - 2013.3

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    Country: Japan

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Research History

  • 日本学術振興会 特別研究員 (DC2)

    2016.4 - 2018.3

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Professional Memberships

 

Papers

  • Spin-orbit-derived giant magnetoresistance in a layered magnetic semiconductor AgCrSe2 Reviewed

    Hidefumi Takahashi, Tomoki Akiba, Alex Hiro Mayo, Kazuto Akiba, Atsushi Miyake, Masashi Tokunaga, Hitoshi Mori, Ryotaro Arita, Shintaro Ishiwata

    Phys. Rev. Mater.   6   054602   2022.5

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

    DOI: 10.1103/physrevmaterials.6.054602

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    Other Link: http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevMaterials.6.054602/fulltext

  • Magnetotransport studies of the Sb square-net compound LaAgSb2 under high pressure and rotating magnetic fields Reviewed

    Kazuto Akiba, Nobuaki Umeshita, Tatsuo C. Kobayashi

    Phys. Rev. B   105   035108   2022.1

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Physical Society (APS)  

    DOI: 10.1103/physrevb.105.035108

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    Other Link: http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevB.105.035108/fulltext

  • Successive destruction of charge density wave states by pressure in LaAgSb2 Reviewed

    K. Akiba, H. Nishimori, N. Umeshita, T. C. Kobayashi

    Phys. Rev. B   103   085134-1 - 085134-13   2021.2

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  • Domain Control by Adjusting Anisotropic Stress in Pyrochlore Oxide Cd2Re2O7 Reviewed

    S. Tajima, D. Hirai, Y. Kinoshita, M. Tokunaga, K. Akiba, T. C. Kobayashi, H. T. Hirose, and Z. Hiroi

    J. Phys. Soc. Jpn.   89   114711-1 - 114711-14   2020.10

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    DOI: 10.7566/JPSJ.89.114711

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  • Anomalous Hall effect triggered by pressure-induced magnetic phase transition in α-Mn Reviewed

    K. Akiba, K. Iwamoto, T. Sato, S. Araki, and T. C. Kobayashi

    Phys. Rev. Research   2 ( 4 )   043090-1 - 043090-6   2020.10

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

    DOI: 10.1103/PhysRevResearch.2.043090

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  • Magnetotransport properties of tellurium under extreme conditions Reviewed

    K. Akiba, K. Kobayashi, T. C. Kobayashi, R. Koezuka, A. Miyake, J. Gouchi, Y. Uwatoko, and M. Tokunaga

    Phys. Rev. B   101   245111-1 - 245111-6   2020.6

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  • Pressure-Temperature Phase Diagram of α-Mn Reviewed

    T. Sato, K. Akiba, S. Araki, and T. C. Kobayashi

    JPS Conf. Proc.   30   011030   2020.3

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  • Bidirectional surface photovoltage on a topological insulator Reviewed

    T. Yoshikawa, K. Sumida, Y. Ishida, J. Chen, M. Nurmamat, K. Akiba, A. Miyake, M. Tokunaga, K. A. Kokh, O. E. Tereshchenko, S. Shin, and A. Kimura

    Phys. Rev. B   100   165311   2019.10

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  • Large Enhancement of Thermoelectric Efficiency Due to a Pressure-Induced Lifshitz Transition in SnSe Reviewed

    T.Nishimura, H.Sakai, H.Mori, K.Akiba, H.Usui, M.Ochi, K.Kuroki, A.Miyake, M.Tokunaga, Y.Uwatoko, K.Katayama, H.Murakawa, N.Hanasaki

    Physical Review Letters   122 ( 22 )   226601-1-6   2019.6

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    © 2019 American Physical Society. The Lifshitz transition, a change in Fermi surface topology, is likely to greatly influence exotic correlated phenomena in solids, such as high-temperature superconductivity and complex magnetism. However, since the observation of Fermi surfaces is generally difficult in the strongly correlated systems, a direct link between the Lifshitz transition and quantum phenomena has been elusive so far. Here, we report a marked impact of the pressure-induced Lifshitz transition on thermoelectric performance for SnSe, a promising thermoelectric material without a strong electron correlation. By applying pressure up to 1.6 GPa, we have observed a large enhancement of the thermoelectric power factor by more than 100% over a wide temperature range (10-300 K). Furthermore, the high carrier mobility enables the detection of quantum oscillations of resistivity, revealing the emergence of new Fermi pockets at ∼0.86 GPa. The observed thermoelectric properties linked to the multivalley band structure are quantitatively reproduced by first-principles calculations, providing novel insight into designing the SnSe-related materials for potential valleytronic as well as thermoelectric applications.

    DOI: 10.1103/PhysRevLett.122.226601

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  • Quantized surface transport in topological Dirac semimetal films Reviewed

    S. Nishihaya, M. Uchida, Y. Nakazawa, R. Kurihara, K. Akiba, M. Kriener, A. Miyake, Y. Taguchi, M. Tokunaga, M. Kawasaki

    Nature Communications   10 ( 1 )   2564   2019.6

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    © 2019, The Author(s). Unconventional surface states protected by non-trivial bulk orders are sources of various exotic quantum transport in topological materials. One prominent example is the unique magnetic orbit, so-called Weyl orbit, in topological semimetals where two spatially separated surface Fermi-arcs are interconnected across the bulk. The recent observation of quantum Hall states in Dirac semimetal Cd3As2 bulks have drawn attention to the novel quantization phenomena possibly evolving from the Weyl orbit. Here we report surface quantum oscillation and its evolution into quantum Hall states in Cd3As2 thin film samples, where bulk dimensionality, Fermi energy, and band topology are systematically controlled. We reveal essential involvement of bulk states in the quantized surface transport and the resultant quantum Hall degeneracy depending on the bulk occupation. Our demonstration of surface transport controlled in film samples also paves a way for engineering Fermi-arc-mediated transport in topological semimetals.

    DOI: 10.1038/s41467-019-10499-0

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  • Topological transitions among skyrmion- and hedgehog-lattice states in cubic chiral magnets Reviewed

    Y. Fujishiro, N. Kanazawa, T. Nakajima, X.Z. Yu, K. Ohishi, Y. Kawamura, K. Kakurai, T. Arima, H. Mitamura, A. Miyake, K. Akiba, M. Tokunaga, A. Matsuo, K. Kindo, T. Koretsune, R. Arita, Y. Tokura

    Nat. Commun.   10   1059   2019.3

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  • Thermodynamic evidence of magnetic-field-induced complete valley polarization in bismuth Reviewed

    A. Iwasa, A. Kondo, S. Kawachi, K. Akiba, Y. Nakanishi, M. Yoshizawa, M. Tokunaga, and K. Kindo

    Sci. Rep.   9   1672   2019.2

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  • Impact of antiferromagnetic order on Landau-level splitting of quasi-two-dimensional Dirac fermions in EuMnBi2 Reviewed

    H. Masuda, H. Sakai, M. Tokunaga, M. Ochi, H. Takahashi, K. Akiba, A. Miyake, K. Kuroki, Y. Tokura, S. Ishiwata

    Phys. Rev. B   98   161108(R)-1-6 - 6   2018.10

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  • Negative magnetoresistance suppressed through a topological phase transition in (Cd1-xZnx)As2 thin films Reviewed

    S. Nishihaya, M. Uchida, Y. Nakazawa, K. Akiba, M. Kriener, Y. Kozuka, A. Miyake, Y. Taguchi, M. Tokunaga, M. Kawasaki

    97   245103   2018.6

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  • Quantitative evaluation of Dirac physics in PbTe Reviewed

    K. Akiba, A. Miyake, H. Sakai, K. Katayama, H. Murakawa, N. Hanasaki, S. Takaoka, Y. Nakanishi, M. Yoshizawa, M. Tokunaga

    Phys. Rev. B   98   115144-1-11 - 11   2018

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  • Large magneto-thermopower in MnGe with topological spin texture Reviewed

    Y. Fujishiro, N. Kanazawa, T. Shimojima, A. Nakamura, K. Ishizaka, T. Koretsune, R. Arita, A. Miyake, H. Mitamura, K. Akiba, M. Tokunaga, J. Shiogai, S. Kimura, S. Awaji, A. Tsukazaki, A. Kikkawa, Y. Taguchi, Y. Tokura

    Nature Communications   9 ( 1 )   408-1-7 - 7   2018

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

    DOI: 10.1038/s41467-018-02857-1

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    Other Link: http://www.nature.com/articles/s41467-018-02857-1.pdf

  • Observation of Poiseuille Flow of Phonons in Black Phosphorus Reviewed

    Y. Machida, A. Subedi, K. Akiba, A. Miyake, M. Tokunaga, Y. Akahama, K. Izawa, K. Behnia

    Sci. Adv.   4   eaat3374-1-9 - 9   2018

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  • Quantum Hall states observed in thin films of Dirac semimetal Cd3As2 Reviewed

    Masaki Uchida, Yusuke Nakazawa, Shinichi Nishihaya, Kazuto Akiba, Markus Kriener, Yusuke Kozuka, Atsushi Miyake, Yasujiro Taguchi, Masashi Tokunaga, Naoto Nagaosa, Yoshinori Tokura, Masashi Kawasaki

    NATURE COMMUNICATIONS   8   2274-1-7 - 7   2017.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:NATURE PUBLISHING GROUP  

    A well known semiconductor Cd3As2 has reentered the spotlight due to its unique electronic structure and quantum transport phenomena as a topological Dirac semimetal. For elucidating and controlling its topological quantum state, high-quality Cd3As2 thin films have been highly desired. Here we report the development of an elaborate growth technique of high-crystallinity and high-mobility Cd3As2 films with controlled thicknesses and the observation of quantum Hall effect dependent on the film thickness. With decreasing the film thickness to 10 nm, the quantum Hall states exhibit variations such as a change in the spin degeneracy reflecting the Dirac dispersion with a large Fermi velocity. Details of the electronic structure including subband splitting and gap opening are identified from the quantum transport depending on the confinement thickness, suggesting the presence of a two-dimensional topological insulating phase. The demonstration of quantum Hall states in our high-quality Cd3As2 films paves a road to study quantum transport and device application in topological Dirac semimetal and its derivative phases.

    DOI: 10.1038/s41467-017-02423-1

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  • Two-carrier analyses of the transport properties of black phosphorus under pressure Reviewed

    K. Akiba, A. Miyake, Y. Akahama, K. Matsubayashi, Y. Uwatoko, and M. Tokunaga

    Phys. Rev. B   95   115126-1 - 7   2017.3

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  • Anomalous Quantum Transport Properties in Semimetallic Black Phosphorus Reviewed

    K. Akiba, A. Miyake, Y. Akahama, K. Matsubayashi, Y. Uwatoko, H. Arai, Y. Fuseya, and M. Tokunaga

    J. Phys. Soc. Jpn.   84   073708-1 - 4   2015.6

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  • Possible Excitonic Phase of Graphite in the Quantum Limit State Reviewed

    K. Akiba, A. Miyake, H. Yaguchi, A. Matsuo, K. Kindo, and M. Tokunaga

    J. Phys. Soc. Jpn.   84   054709-1 - 7   2015.4

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  • Anisotropic upper critical field of the BiS2-based superconductor LaO0.5F0.5BiS2 Reviewed

    Y. Mizuguchi, A. Miyake, K. Akiba, M. Tokunaga, J. Kajita, and O. Miura

    Phys. Rev. B   89   174515-1 - 7   2014.3

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Books

MISC

  • Quantum transport phenomena in narrow-gap semiconductors under high pressure and high magnetic field Reviewed

    Review of High Pressure Science and Technology   30   260 - 273   2020.12

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  • PbTeにおける「ディラックネス」の評価 Reviewed

    秋葉和人, 三宅厚志, 徳永将史

    固体物理   54   201 - 213   2019.4

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  • 圧力下の半金属黒燐における異常量子伝導 Reviewed

    秋葉和人, 三宅厚志, 徳永将史, 赤浜裕一

    固体物理   51   249 - 258   2016.4

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Presentations

  • 磁場中・圧力下の電気伝導測定から見るトポロジカル物質の電子状態 Invited

    秋葉和人

    ワークショップ(5)「超伝導物質、トポロジカル物質」(SCTM2021)  2021.11.26 

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    Event date: 2021.11.25 - 2021.11.26

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

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  • Magneto-transport properties of elemental semiconductor tellurium under high pressure and high magnetic field International conference

    K. Akiba, K. Kobayashi, T. C. Kobayashi, R. Koezuka, A. Miyake, J. Gouchi, Y. Uwatoko, M. Tokunaga

    Asian Regional High Magnetic Field Conference (ARHMF2020) 

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    Event date: 2020.12.1 - 2020.12.3

    Language:English   Presentation type:Oral presentation (general)  

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  • α-Mnの圧力誘起磁性相における異常Hall効果

    秋葉和人, 岩本凱成, 佐藤飛諒, 荒木新吾, 小林達生

    日本物理学会2020年秋季大会 

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    Event date: 2020.9.8 - 2020.9.11

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 電荷密度波物質LaAgSb2の圧力下磁気輸送特性

    秋葉和人, 小林達生

    日本物理学会第75回年次大会 

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    Event date: 2020.3.16 - 2020.3.19

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  • Quantum Transport Properties on Chemically Etched (0001) Surface of Tellurium International conference

    K. Akiba, S. Asada, K. Kobayashi, T. C. Kobayashi, R. Koezuka, and M. Tokunaga

    International Conference on Strongly Correlated Electron System 2019 (SCES2019) 

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    Event date: 2019.9.23 - 2019.9.28

    Presentation type:Poster presentation  

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  • 化学エッチングしたTeの(0001)表面における量子輸送現象

    秋葉和人, 浅田翔一朗, 小林夏野, 小林達生, 肥塚遼, 徳永将史

    日本物理学会2019年秋季大会 

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    Event date: 2019.9.10 - 2019.9.13

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  • Pressure-temperature phase diagram of alpha-Mn International conference

    K. Akiba

    Progress in Superconductivity Research -RIIS Mini Workshop- 

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    Event date: 2019.4.23

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

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  • 圧力下におけるPbTeの電気伝導測定

    秋葉和人, 小林達生, 三宅厚志, 酒井英明, 片山敬介, 村川寛, 花咲徳亮, 鷹岡貞夫, 上床美也, 徳永将史

    日本物理学会 第74回年次大会 

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    Event date: 2019.3.14 - 2019.3.17

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  • 量子振動から評価するPbTeの”Diracness”とその圧力変化

    秋葉和人, 三宅厚志, 酒井英明, 片山敬介, 村川寛, 花咲徳亮, 鷹岡貞夫, 中西良樹, 吉澤正人, 小林達生, 徳永将史

    スピン軌道強結合伝導系におけるサイエンスの新展開 

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    Event date: 2018.11.12 - 2018.11.13

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  • PbTeにおける“Diracness”の評価とその圧力依存性

    秋葉和人, 三宅厚志, 酒井英明, 片山敬介, 村川寛, 花咲徳亮, 鷹岡貞夫, 中西良樹, 吉澤正人, 小林達生, 徳永将史

    日本物理学会 秋季大会  2018 

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    Event date: 2018.9.9 - 2018.9.12

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  • Quantitative evaluation of “Diracness” through the quantum oscillation measurements in PbTe International conference

    K. Akiba, A. Miyake, H. Sakai, K. Katayama, H. Murakawa, N. Hanasaki, S. Takaoka, Y. Nakanishi, M. Yoshizawa, and M. Tokunaga

    The 12th International Conference on Research in High Magnetic Fields (RHMF 2018)  2018 

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    Event date: 2018.6.24 - 2018.6.28

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  • Quantitative Evaluation of "Diracness" from the Quantum Oscillations in PbTe International conference

    K. Akiba, A. Miyake, H. Sakai, K. Katayama, T. Sakamoto, N. Hanasaki, S. Takaoka, Y. Nakanishi, M. Yoshizawa, Y. Uwatoko, and M. Tokunaga

    APS March Meeting 2018  2018 

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    Event date: 2018.3.5 - 2018.3.9

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  • 単元素半導体Teの強磁場・圧力下における電気伝導特性

    秋葉和人, 三宅厚志, 小林夏野, 郷地順, 上床美也, 徳永将史

    日本物理学会 秋季大会  2017 

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    Event date: 2017.9.21 - 2017.9.24

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  • Pb1-xSnxTeの強磁場物性

    秋葉和人, 三宅厚志, 酒井英明, 片山敬介, 坂本拓也, 花咲徳亮, 鷹岡貞夫, 中西良樹, 吉澤正人, 上床美也, 徳永将史

    日本物理学会 第72回年次大会 

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    Event date: 2017.3.17 - 2017.3.20

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 強磁場下の量子振動現象から見るPbTeのDiracness

    秋葉和人, 三宅厚志, 酒井英明, 片山敬介, 花咲徳亮, 鷹岡貞夫, 中西良樹, 吉澤正人, 徳永将史

    第二回ディラック電子系マルチフェロイクス研究会  2016 

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    Event date: 2016.11.17 - 2016.11.18

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

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  • パルス強磁場下におけるIV-VI族化合物PbTeの輸送特性

    秋葉和人, 三宅厚志, 酒井英明, 片山敬介, 花咲徳亮, 鷹岡貞夫, 徳永将史

    日本物理学会 秋季大会  2016 

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    Event date: 2016.9.13 - 2016.9.16

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 磁場・圧力下の半金属黒燐における量子輸送現象と電子状態

    秋葉和人, 三宅厚志, 赤浜裕一, 松林和幸, 上床美也, 徳永将史

    東京大学物性研究所短期研究会 「強磁場コラボラトリー、国際協力と強磁場科学」  2016 

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    Event date: 2016.6.23 - 2016.6.24

    Language:Japanese   Presentation type:Poster presentation  

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  • 磁場中・圧力下の電気伝導測定から見る半金属黒燐の電子状態

    秋葉和人, 三宅厚志, 佐藤由昌, 赤浜裕一, 松林和幸, 上床美也, 徳永将史

    短期研究会 低次元電子系におけるエキシトニック相の新展開  2015 

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    Event date: 2015.11.26 - 2015.11.28

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

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  • 高圧下電気抵抗測定から見る半金属黒燐のFermi面

    秋葉和人, 三宅厚志, 佐藤由昌, 赤浜裕一, 松林和幸, 上床美也, 徳永将史

    日本物理学会 秋季大会  2015 

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    Event date: 2015.9.16 - 2015.9.19

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Possible realization of the excitonic BCS state in the quantum limit state in graphite International conference

    K. Akiba, A. Miyake, H. Yaguchi, A. Matsuo, K. Kindo, Y. Iye, and M. Tokunaga

    The 11th International Conference on Research in High Magnetic Fields (RHMF2015)  2015 

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    Event date: 2015.7.1 - 2015.7.4

    Language:English   Presentation type:Poster presentation  

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  • 多重極限下における半金属黒燐の異常量子伝導

    秋葉和人, 三宅厚志, 赤浜裕一, 松林和幸, 上床美也, 徳永将史

    日本物理学会 第70回年次大会  2015 

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    Event date: 2015.3.21 - 2015.3.24

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 圧力下における黒燐の量子振動

    秋葉和人, 三宅厚志, 赤浜裕一, 松林和幸, 上床美也, 徳永将史

    強磁場科学研究会 強磁場が切り拓く物質科学のフロンティア  2014 

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    Event date: 2014.12.4 - 2014.12.5

    Language:Japanese   Presentation type:Poster presentation  

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  • パルス強磁場下における黒リンの磁気抵抗測定 International conference

    秋葉和人, 三宅厚志, 赤浜裕一, 徳永将史

    日本物理学会 秋季大会  2014 

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    Event date: 2014.9.7 - 2014.9.10

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  • グラファイトの密度波相における電気伝導特性の形状効果

    秋葉和人, 三宅厚志, 矢口宏, 徳永将史

    日本物理学会 第69回年次大会  2014 

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    Event date: 2014.3.27 - 2014.3.30

    Language:Japanese   Presentation type:Poster presentation  

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  • パルス強磁場におけるグラファイトの電気伝導および磁化測定

    秋葉和人, 三宅厚志, 矢口宏, 松尾晶, 金道浩一, 徳永将史

    東京大学物性研究所短期研究会「極限強磁場科学-場、物質、プローブのリンクから融合へ」  2013 

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    Event date: 2013.10.30 - 2013.11.1

    Language:Japanese   Presentation type:Poster presentation  

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  • 75 Tまでのパルス強磁場におけるグラファイトの磁気輸送特性

    秋葉和人, 三宅厚志, 矢口宏, 松尾晶, 金道浩一, 徳永将史

    日本物理学会 秋季大会  2013 

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    Event date: 2013.9.25 - 2013.9.28

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 電荷密度波物質LaAgSb2における圧力下量子輸送現象の磁場方位依存性

    秋葉和人, 梅下暢朗, 小林達生

    日本物理学会 2021年秋季大会  2021.9 

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  • LaAgSb2における電荷密度波の圧力温度相図と圧力下におけるFermi面の変化

    秋葉和人, 西森弘顕, 梅下暢朗, 小林達生

    日本物理学会 第76回年次大会  2021.3 

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  • The evaluation of Diracness in Pb1-xSnxTe from the quantum oscillation phenomena in magnetic fields

    K. Akiba, A. Miyake, H. Sakai, K. Katayama, T. Sakamoto, N. Hanasaki, S. Takaoka, Y. Nakanishi, M. Yoshizawa, Y. Uwatoko, M. Tokunaga

    International Conference on Strongly Correlated Electron Systems (SCES 2017)  2017.7 

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Awards

  • 理学系研究科研究奨励賞

    2018  

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    Country:Japan

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Research Projects

  • Function creation in polar metals

    Grant number:21H01030  2021.04 - 2024.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

    高橋 英史, 中埜 彰俊, 秋葉 和人

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    Authorship:Coinvestigator(s) 

    Grant amount:\17810000 ( Direct expense: \13700000 、 Indirect expense:\4110000 )

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  • 圧力下のPbTeにおけるトポロジカル電子相実現の実証とその物性解明

    Grant number:19K14660  2019.04 - 2022.03

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

    秋葉 和人

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    Authorship:Principal investigator 

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

    本年度の研究計画は、圧力下におけるPbTeの電気抵抗およびHall抵抗を測定し、量子振動からZeemanサイクロトロン比(ZC比)の圧力依存性を明らかにすることであった。これに対して、本年度に得られた研究成果を示す。
    まず対向アンビル型圧力セルによる磁気輸送特性の測定を行った。その結果、加圧に従って量子振動が変化し、2 GPa付近で位相反転が見られた。これはZC比が1となる際に予想される振る舞いであり、2 GPa付近でバンドギャップが零となっていることを示唆している。その後、より細かく圧力を制御してZC比の圧力依存性を明らかにするために、インデンター型圧力セルによる同様の実験を行った。しかしその際、量子振動が常圧から4 GPa付近まで変化せず、ZC比が変化しない場合があることが確認された。これらの実験では圧力セルが異なるものの共通の圧力媒体を用いており、Hall抵抗から求められたキャリア数にもほとんど違いがないことが分かっている。現在、この違いを生じる原因の特定を進めている。また本研究で用いているZC比による電子構造の評価は、他の物質でも有効であると考えられる。これを明らかにするために、単元素Teや、電荷密度波物質LaAgSb2における磁気輸送特性の測定も行い、どちらの物質においても明瞭なShubnikov-de Haas振動を観測した。Teに関しては、その量子振動の起源が表面の電荷蓄積層であることを明らかにした。今後の解析によってこれらの物質でもZC比によるディラックネスの評価が有効であるかどうかを明らかにする予定である。
    本年度の間に、PbTeにおける「ディラックネス」の決定を解説した日本語記事、およびPbTeの量子振動測定の結果を含む書籍が出版された。またTeとLaAgSb2に関して得られた成果を国内学会および国際学会において発表した。

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Class subject in charge

  • Information Physics Experiments 2 (2021academic year) 3rd and 4th semester  - 月5,月6,月7,月8

  • Information Physics Experiments 2 (2021academic year) 3rd and 4th semester  - 月5,月6,月7,月8

  • Physics of Materials under Extreme Conditions (2021academic year) Late  - 金3,金4

  • Physics Experiments 2 (2021academic year) 3rd and 4th semester  - [第3学期]月5,月6,月7,月8, [第4学期]月4,月5,月7,月8

  • Information Physics Experiments 2 (2020academic year) 3rd and 4th semester  - 月3,月4,月5,月6

  • Information Physics Experiments 2 (2020academic year) 3rd and 4th semester  - 月3,月4,月5,月6

  • Physics of Materials under Extreme Conditions (2020academic year) Late  - 金2,金3

  • Physics Experiments 2 (2020academic year) 3rd and 4th semester  - 月3,月4,月5,月6

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