時間・スピン分解光電子分光によるディラック電子系のスピンダイナミクスの研究

• Project/Area Number: 16J03874
• Research Category: Grant-in-Aid for JSPS Fellows
• Allocation Type: Single-year Grants
• Section: 国内
• Research Field: Condensed matter physics I
• Research Institution: Hiroshima University
• Principal Investigator: 角田 一樹 広島大学, 理学研究科, 特別研究員(DC1)
• Project Period (FY): 2016-04-22 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥3,300,000 (Direct Cost: ¥3,300,000); Fiscal Year 2018: ¥1,000,000 (Direct Cost: ¥1,000,000); Fiscal Year 2017: ¥1,100,000 (Direct Cost: ¥1,100,000); Fiscal Year 2016: ¥1,200,000 (Direct Cost: ¥1,200,000)
• Keywords: 時間分解光電子分光 / スピン分解光電子分光 / ディラック電子系 / トポロジカル絶縁体 / 超高速現象 / 強磁性トポロジカル絶縁体 / レーザー

Outline of Annual Research Achievements

トポロジカル絶縁体やグラフェンに代表されるディラック電子系は、波数空間上で円錐型バンド分散を形成し、多彩な物性を示すことで知られる。本研究では主に、トポロジカル絶縁体表面に現れるスピン偏極ディラック電子に着目し、スピン分解および時間分解光電子分光によってそのスピン偏極電子状態と超高速キャリアダイナミクスを観測した。
本年度は、昨年度に引き続き、p型トポロジカル絶縁体(Sb0.73Bi0.27)2Te3について時間分解光電子分光を行い、超高速キャリアダイナミクスの温度依存性を詳細に追跡した。その結果、ディラック点の上下で過渡的な反転分布が形成されていることを実験的に見出した。また、この反転分布は室温で10ピコ秒以上持続することが明らかとなり、今後、トポロジカル絶縁体(Sb,Bi)2Te3を用いた有限温度での広帯域レーザー発振の実現が期待される（Physical Review B誌に掲載）。
また、本研究で開発を進めた10ミクロン以下の空間分解能を持つスピン分解光電子分光装置を用いて鉛系トポロジカル絶縁体PbBi4Te4S3の顕微分光を行い、表面終端構造に依存した2種類のスピン偏極表面状態の分離観測に成功した。観測された表面状態の一つは酸素暴露の影響をほとんど受けず、最表面に保護された純スピン流の創生が期待される（Physical Review Materials誌に掲載）。
更に、トポロジカル絶縁体に磁性不純物を加えた希薄磁性トポロジカル絶縁体(Sb1-xVx)2Te3について、磁気円二色性分光、走査トンネル顕微鏡・分光、時間分解光電子分光を行い、磁性不純物が与える影響を磁性・構造・電子状態・キャリアダイナミクスの観点から明らかにした。その結果、Vが作る不純物状態がバンド間散乱を誘起し、励起電子の緩和時間が大幅に短くなることが明らかとなった（論文査読中）。

Research Progress Status

平成30年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

平成30年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] Inverted Dirac-electron population in a thermally activated topological insulator (2019)
  • Author(s): K. Sumida, Y. Ishida, T. Yoshikawa, J. Chen, M. Nurmamat, K. A. Kokh, O. E. Tereshchenko, S. Shin, and A. Kimura
  • Journal Title: Phys. Rev. B Volume: 99 Issue: 8 Pages: 085302-085302
  • DOI: 10.1103/physrevb.99.085302
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] A general route to form topologically-protected surface and bulk Dirac fermions along high-symmetry lines (2019)
  • Author(s): Clark O J、Mazzola F、Markovic I、Riley J M、Feng J、Yang B-J、Sumida K、Okuda T、Fujii J、Vobornik I、Kim T K、Okawa K、Sasagawa T、Bahramy M S、King P D C
  • Journal Title: Electronic Structure Volume: 1 Issue: 1 Pages: 014002-014002
  • DOI: 10.1088/2516-1075/ab09b7
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Negative Te spin polarization responsible for ferromagnetic order in the doped topological insulator V0.04(Sb1-xBix)1.96Te3 (2019)
  • Author(s): M. Ye, T. Xu, G. Li, S. Qiao, Y. Takeda, Y. Saitoh, S.-Y. Zhu, M. Nurmamat, K. Sumida, Y. Ishida, S. Shin, and A. Kimura
  • Journal Title: Physical Review B Volume: 99 Issue: 14
  • DOI: 10.1103/physrevb.99.144413
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Enhanced photovoltage on the surface of topological insulator by optical aging (2018)
  • Author(s): Tomoki Yoshikawa, Yukiaki Ishida, Kazuki Sumida, Jiahua Chen, Konstantin, A. Kokh, Oleg E. Tereshchenko, Shik Shin, and Akio Kimura
  • Journal Title: Appl. Phys. Lett. Volume: 112 Issue: 19 Pages: 192014-192014
  • DOI: 10.1063/1.5008466
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Shubnikov-de Haas oscillations in p and n-type topological insulator (BixSb1-x)2Te3 (2018)
  • Author(s): Ryota Akiyama, Kazuki Sumida, Satoru Ichinokura, Ryosuke Nakanishi1, Akio Kimura2, Konstantin A Kokh, Oleg E Tereshchenko, and Shuji Hasegawa
  • Journal Title: Journal of Physics: Condensed Matter Volume: 30 Issue: 26 Pages: 265001-265001
  • DOI: 10.1088/1361-648x/aac59b
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Prolonged photo-carriers generated in a massive-and-anisotropic Dirac material (2018)
  • Author(s): Nurmamat Munisa、Ishida Yukiaki、Yori Ryohei、Sumida Kazuki、Zhu Siyuan、Nakatake Masashi、Ueda Yoshifumi、Taniguchi Masaki、Shin Shik、Akahama Yuichi、Kimura Akio
  • Journal Title: Scientific Reports Volume: 8 Issue: 1 Pages: 1-7
  • DOI: 10.1038/s41598-018-27133-6
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Enhanced surface state protection and band gap in the topological insulator PbBi4Te4S3 (2018)
  • Author(s): K. Sumida, T. Natsumeda, K. Miyamoto, I. V. Silkin, K. Kuroda, K. Shirai, S. Zhu, K. Taguchi, M. Arita, J. Fujii, A. Varykhalov, O. Rader, V. A. Golyashov, K. A. Kokh, O. E. Tereshchenko, E. V. Chulkov, T. Okuda, and A. Kimura
  • Journal Title: PHYSICAL REVIEW MATERIALS Volume: 2 Issue: 10 Pages: 104201-104201
  • DOI: 10.1103/physrevmaterials.2.104201
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Multiple topological states in iron-based superconductors (2018)
  • Author(s): P.Zhang, Z. Wang, X. Wu, K. Yaji, Y. Ishida, Y. Kohama, G. Dai, Y. Sun, C. Bareille1, K. Kuroda, T. Kondo1, K. Okazaki, K. Kindo1, X. Wang, C. Jin, J. Hu, R. Thomale, K. Sumida, S. Wu, K. Miyamoto, T. Okuda, H. Ding, G. D. Gu, T. Tamegai, T. Kawakami, M. Sato, S. Shin
  • Journal Title: Nature Physics Volume: 15 Issue: 1 Pages: 41-47
  • DOI: 10.1038/s41567-018-0280-z
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Ultrafast dynamics of unoccupied surface resonances state of Bi2Te2Se (2018)
  • Author(s): Munisa Nurmamat, K. Sumida, Y. Ishida, J. Chen, T. Yoshikawa, E. E. Krasovskii, K. A. Kokh, O. E. Tereshchenko, Shik Shin and Akio Kimura
  • Journal Title: Phys. Rev. B Volume: 97 Issue: 11 Pages: 115303-115303
  • DOI: 10.1103/physrevb.97.115303
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Experimental realization of type-II Weyl state in non-centrosymmetric TaIrTe4 (2017)
  • Author(s): E. Haubold, K. Koepernik, D. Efremov, S. Khim, A. Fedorov, Y. Kushnirenko, J. van den Brink, S. Wurmehl, B. B_chner, T. K. Kim, M. Hoesch, K. Sumida, K. Taguchi, T. Yoshikawa, A. Kimura, T. Okuda and S. V. Borisenko
  • Journal Title: Phys. Rev. B Volume: 7 Issue: 24
  • DOI: 10.1103/physrevb.95.241108
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Large-Gap Magnetic Topological Heterostructure Formed by Subsurface Incorporation of a Ferromagnetic Layer (2017)
  • Author(s): T. Hirahara, S. V. Eremeev, T. Shirasawa, Y. Okuyama, T. Kubo, R. Nakanishi, R. Akiyama, A. Takayama, T. Hajiri, S. Ideta, M. Matsunami, K. Sumida, K. Miyamoto, Y. Takagi, K. Tanaka, T. Okuda, T. Yokoyama, S. Kimura, S. Hasegawa, E. V. Chulkov
  • Journal Title: NANO Letters Volume: 17 Issue: 6 Pages: 3493-3500
  • DOI: 10.1021/acs.nanolett.7b00560
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Prolonged duration of nonequilibrated Dirac fermions in neutral topological insulators (2017)
  • Author(s): K. Sumida, Y. Ishida, S. Zhu, M. Ye, K. A. Kokh, O. E. Tereshchenko, S. Shin, and A. Kimura
  • Journal Title: Scientific Reports Volume: 7 Issue: 1
  • DOI: 10.1038/s41598-017-14308-w
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Direct evidence of hidden local spin polarization in a centrosymmetric superconductor LaO0.55F0.45BiS2 (2017)
  • Author(s): Shi-Long Wu, Kazuki Sumida, Koji Miyamoto, Kazuaki Taguchi, Tomoki Yoshikawa, Akio Kimura, Yoshifumi Ueda, Masashi Arita, Masanori Nagao, Satoshi Watauchi, Isao Tanaka and Taichi Okuda
  • Journal Title: Nature Communications Volume: 8 Issue: 1
  • DOI: 10.1038/s41467-017-02058-2
  • Peer Reviewed / Open Access
• [Journal Article] Surface Kondo Effect and Non-Trivial Metallic State of the Kondo Insulator YbB12 (2016)
  • Author(s): K. Hagiwara, Y. Ohtsubo, M. Matsunami, S. Ideta, K. Tanaka, H. Miyazaki, J. Rault, P. Le Fevre, F. Bertran, A. Taleb-Ibrahimi, R. Yukawa, M. Kobayashi, K. Horiba, H. Kumigashira, K. Sumida, T. Okuda, F. Iga, S. Kimura
  • Journal Title: Nature Communications Volume: 7 Issue: 1
  • DOI: 10.1038/ncomms12690
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Presentation] Enhanced Surface State Protection and Band Gap in the Topological Insulator PbBi4Te4S3 (2019)
  • Author(s): K. Sumida, T. Natsumeda, K. Miyamoto, I. V. Silkin, K. Kuroda, K. Shirai, S. Zhu, K. Taguchi, M. Arita, J. Fujii, A. Varykhalov, O. Rader, V. A. Golyashov, K. A. Kokh, O. E. Tereshchenko, E. V. Chulkov, T. Okuda, and A. Kimura
  • Organizer: The 23rd Hiroshima International Symposium on Synchrotron Radiation
  • Int'l Joint Research
• [Presentation] 光電子分光で捉えるCo基磁性形状記憶合金の電子状態 (2018)
  • Author(s): 角田一樹
  • Organizer: 第25回みちのく磁性談話会
  • Invited
• [Presentation] Ultrafast carrier dynamics and transient population inversion of the topological insulators (Sb,Bi)2Te3 (2018)
  • Author(s): K. Sumida, Y. Ishida, T. Yoshikawa, J. Chen, M. Nurmamat, K. A. Kokh, O. E. Tereshchenko, S. Shin, and A. Kimura
  • Organizer: New Trends in Topological Insulators 2018 and 18th International Conference on Narrow Gap Systems
  • Int'l Joint Research
• [Presentation] トポロジカル絶縁体(Sb,Bi)2Te3における反転分布現象の観測と制御 (2018)
  • Author(s): 角田一樹, 石田行章, 吉川智己, 陳家華, M. Nurmamat, K. A. Kokh, O. E. Tereshchenko, 辛埴, 木村昭夫
  • Organizer: 日本物理学会2018年年次大会
• [Presentation] Inverted Dirac-population in a thermally activated topological insulator (2018)
  • Author(s): Kazuki Sumida, Yukiaki Ishida, Tomoki Yoshikawa, Jiahua Chen, Munisa Nurmamat, Konstantin Kokh, Oleg Tereshchenko, Shik Shin, and Akio Kimura
  • Organizer: International workshop “Variety and universality of bulk-edge correspondence in topological phases : From solid state physics to transdisciplinary concepts”
  • Int'l Joint Research
• [Presentation] Population inversion in topological insulators (Sb,Bi)2Te3 (2018)
  • Author(s): Kazuki Sumida, Yukiaki Ishida, Tomoki Yoshikawa, Jiahua Chen, Munisa Nurmamat, Konstantin Kokh, Oleg Tereshchenko, Shik Shin, and Akio Kimura
  • Organizer: The 1st International Workshop on Emergent Condensed Matter Physics
  • Int'l Joint Research
• [Presentation] Present Status of 6eV Laser Based Spin-ARPES system (2018)
  • Author(s): K. Sumida, K. Miyamoto, E. Annese, K. Taguchi, K. Shimada, A. Kimura, and T. Okuda
  • Organizer: The 22nd Hiroshima International Symposium on Synchrotron Radiation
  • Int'l Joint Research
• [Presentation] 磁性トポロジカル絶縁体の超高速キャリアダイナミクス (2017)
  • Author(s): 角田一樹, 石田行章, K. A. Kokh, O. E. Tereshchenko, 辛埴, 木村昭夫
  • Organizer: 科研費基盤研究会A (26247064) 第6回研究会 -トポロジカル相におけるバルク・エッジ対応の物理とその普遍性：固体物理から冷却原子まで-
  • Place of Presentation: 筑波大学
  • Year and Date: 2017-03-22
• [Presentation] 磁性トポロジカル絶縁体の超高速キャリアダイナミクス (2017)
  • Author(s): 角田一樹, 石田行章, K. A. Kokh, O. E. Tereshchenko, 辛埴, 木村昭夫
  • Organizer: 日本物理学会2017年・年次大会
  • Place of Presentation: 大阪大学
  • Year and Date: 2017-03-17
• [Presentation] Surface Dirac Fermion Dynamics of Non-Magnetic and Magnetic Topological Insulators (2017)
  • Author(s): K. Sumida, Y. Ishida, T. Yoshikawa, J. Chen, M. Nurmamat, K. Kokh, O. Tereshchenko, S. Shin, A. Kimura
  • Organizer: Symposium on Surface Science & Nanotechnology -25th Anniversary of SSSJ Kansai-
  • Place of Presentation: Kyoto International Community House
  • Year and Date: 2017-01-24
  • Int'l Joint Research
• [Presentation] 硬X線光電子分光によるホイスラー合金Co2Cr(Ga,Si)の電子状態の研究 (2017)
  • Author(s): 角田一樹、辻川雅人、許皛、上田茂典、陳家華、朱思源、 白井正文、貝沼亮介、木村昭夫
  • Organizer: 第30会日本放射光学会年会・放射光科学合同シンポジウム
  • Place of Presentation: 神戸芸術センター
  • Year and Date: 2017-01-07
• [Presentation] 鉛系トポロジカル絶縁体PbBi4Te4S3のスピン角度分解光電子分光 (2017)
  • Author(s): 角田一樹, 棗田翼, 白井開渡, 黒田健太, 朱思源, 田口一暁, 宮本幸治, 奥田太一, 有田将司, 生天目博文, 谷口雅樹, 藤井純, K. A. Kokh, O. E. Tereshchenko, E. V. Chulkov, 木村昭夫
  • Organizer: スタートアップ研究会基盤研究S「トポロジカル相でのバルク・エッジ対応の多様性と普遍性：固体物理を超えて分野横断へ」
• [Presentation] 放射光分光及び第一原理計算を用いたホイスラー合金Co2Cr(Ga,Si)の電子状態の研究 (2017)
  • Author(s): 角田一樹, 辻川雅人, 許皛, 上田茂典, 陳家華, 朱思源, 吉川智己, 檜垣聡太, 竹田幸治, 斎藤祐児, 白井正文, 貝沼亮介, 木村昭夫
  • Organizer: 日本金属学会2017年秋期講演大会
• [Presentation] 磁性トポロジカル絶縁体(Sb1-xVx)2Te3のキャリア誘起強磁性および超高速キャリアダイナミクス (2017)
  • Author(s): 角田一樹, 石田行章, 吉川智己, 檜垣聡太, K. A. Kokh, O. E. Tereshchenko, 竹田幸治, 斎藤祐児, 辛埴, 木村昭夫
  • Organizer: 日本物理学会2017年秋季大会
• [Presentation] ホイスラー合金Co2Cr(Ga,Si)におけるリエントラント・マルテンサイト変態機構 (2017)
  • Author(s): 角田一樹, 辻川雅人, 許皛, 陳家華, 朱思源, 吉川智己, 檜垣聡太, 上田茂典, 竹田幸治, 斎藤祐児, 白井正文, 貝沼亮介, 木村昭夫
  • Organizer: 日本物理学会2017年秋季大会
• [Presentation] Ultrafast Surface Dirac Fermion Dynamics of Sb2Te3-based Topological Insulators (2017)
  • Author(s): Kazuki Sumida, Yukiaki Ishida, Tomoki Yoshikawa, Jiahua Chen, Munisa Nurmamat, Konstantin Kokh, Oleg Tereshchenko, Shik Shin, and Akio Kimura
  • Organizer: Superstripes2017
  • Int'l Joint Research / Invited
• [Presentation] Temperature-induced prolonged duration of non-equilibrium surface Dirac fermions in topological insulators (2017)
  • Author(s): Kazuki Sumida, Yukiaki Ishida, Tomoki Yoshikawa, Jiahua Chen, Munisa Nurmamat, Konstantin Kokh, Oleg Tereshchenko, Shik Shin, and Akio Kimura
  • Organizer: 10th International Symposium on Ultrafast Surface Dynamics
  • Int'l Joint Research
• [Presentation] Ultrafast surface Dirac fermions dynamics of magnetic topological insulator (Sb1-xVx)2Te3 (2017)
  • Author(s): Kazuki Sumida, Yukiaki Ishida, Konstantin A. Kokh, Oleg E. Tereshchenko, Shik Shin, and Akio Kimura
  • Organizer: The 17th International workshop on strong correlations and angle-resolved photoemission spectroscopy
  • Int'l Joint Research
• [Presentation] Ultrafast surface carrier dynamics of magnetically doped topological insulators (2017)
  • Author(s): Kazuki Sumida, Yukiaki Ishida, Konstantin A. Kokh, Oleg E. Tereshchenko, Shik Shin, and Akio Kimura
  • Organizer: New Trends in Topological Insulators 2017
  • Int'l Joint Research
• [Presentation] Unveiling reentrant martensitic phase transition mechanism in Co2Cr(Ga,Si) Heusler alloys (2017)
  • Author(s): K. Sumida, M. Tsujikawa, X. Xu, J. Chen, S. Zhu, T. Yoshikawa, S. Higaki, S. Ueda, Y. Takeda, Y. Saitoh, M. Shirai, R. Kainuma, and A. Kimura
  • Organizer: Junjiro Kanamori Memorial International Symposium -New Horizon of Magnetism-
  • Int'l Joint Research
• [Presentation] Long duration of non-equilibrium Dirac fermions in topological insulator (Sb,Bi)2Te3 (2016)
  • Author(s): Kazuki Sumida
  • Organizer: Physics of bulk-edge correspondence & its universality From solid state physics to cold atoms International workshop
  • Place of Presentation: Kyoto University
  • Year and Date: 2016-09-27
  • Int'l Joint Research
• [Presentation] トポロジカル絶縁体(Sb,Bi)2Te3の非平衡キャリアダイナミクスの温度依存性 (2016)
  • Author(s): 角田一樹, 石田行章, 吉川智己, 陳家華, M. Nurmamat, K. A. Kokh, O. E. Tereshchenko, 辛埴, 木村昭夫
  • Organizer: 日本物理学会2016年・秋季大会
  • Place of Presentation: 金沢大学
  • Year and Date: 2016-09-12
• [Presentation] Dirac fermion dynamics in carrier tuned topological insulators (2016)
  • Author(s): K. Sumida, Y. Ishida, S. Zhu, M. Ye, K. A. Kokh, O. E. Tereshchenko, S. Shin, and A. Kimura
  • Organizer: 39th International Conference on Vacuum Ultraviolet and X-ray Physics
  • Place of Presentation: ETH Zurich, Switzerland
  • Year and Date: 2016-07-03
  • Int'l Joint Research
• [Presentation] Dirac fermion dynamics in the topological insulators (Sb1-xBix)2Te3 (2016)
  • Author(s): Kazuki Sumida
  • Organizer: EMN Prague meeting
  • Place of Presentation: Grandior Prague Hotel, Czech Republic
  • Year and Date: 2016-06-21
  • Int'l Joint Research / Invited
• [Remarks] 黒リンにおける電子のたたき上げ現象を世界で初めて観測 ～次世代の超高速通信デバイスの素材として期待～
  • URL: https://www.hiroshima-u.ac.jp/sci/news/45800
• [Remarks] トポロジカル絶縁体に付与した光情報の持続時間を飛躍的に長くすることに成功
  • URL: https://www.hiroshima-u.ac.jp/news/42287
• [Remarks] 新奇超伝導体に特殊なスピン電子構造を発見 －スピントロニクスデバイス開発と超伝導研究に新たな光－
  • URL: https://www.hiroshima-u.ac.jp/news/42893
• [Remarks] トポロジカル絶縁体を強磁性にする新たな方法を発見 －量子異常ホール効果を利用したデバイス開発へ進展－
  • URL: https://www.hiroshima-u.ac.jp/news/39806
• [Remarks] トポロジカル近藤絶縁体の特異な2次元電子状態を発見
  • URL: http://www.hsrc.hiroshima-u.ac.jp/research/result/37.html