重い電子の人工制御

2014 Fiscal Year Annual Research Report

• Project/Area Number: 25220710
• Research Institution: Kyoto University
• Principal Investigator: 松田 祐司 京都大学, 理学(系)研究科(研究院), 教授 (50199816)
• Co-Investigator(Kenkyū-buntansha): 芝内 孝禎 東京大学, 新領域創成科学研究科, 教授 (00251356) ; 笠原 成 京都大学, 理学(系)研究科(研究院), 助教 (10425556) ; 花栗 哲郎 国立研究開発法人理化学研究所, その他部局等, その他 (40251326) ; 寺嶋 孝仁 京都大学, 学内共同利用施設等, 教授 (40252506)
• Project Period (FY): 2013-05-31 – 2018-03-31
• Keywords: 重い電子 / 超伝導 / 人工超格子 / 量子臨界点 / 空間反転対称性 / 界面制御 / 分子線エピタキシー / 走査型トンネル顕微鏡

Outline of Annual Research Achievements

当該研究は、これまで不可能であった重い電子の人工制御により自然界には存在しない2次元重い電子系物質を人工創製し、新奇な電子状態やエキゾチックな超伝導状態の創出と解明、更には、関連する重い電子系物質や鉄系超伝導体などの非従来型超伝導における電子状態、超伝導状態の包括的な解明を目的とする．

① 本プロジェクトでは、重要課題の一つとして、独自の希土類分子線エピタキシー(MBE)装置と走査型トンネル顕微鏡(STM)装置を結合させたMBE-STM一体装置の開発を行い、バルク結晶では不可能であった原子レベルで平坦かつ清浄な表面における重い電子状態の「その場観察」と解明に取り組んでいる．本年度は、初年度に引き続き、同装置の立ち上げに取り組んだ．MBE装置では原子レベルで平坦な高品質の重い電子系エピタキシャル薄膜が再現性良く得られていることが高速電子線回折像とX線回折から確認された．また、STM測定においては特に種々のノイズ対策と鉄系超伝導体バルク単結晶を用いた試験測定を行い、原子の鮮明なトポグラフ像とトンネルスペクトルが得られるようになった．

② 現有のMBE装置を用いて、様々な人工超格子の作製に取り組んだ。特に、層状重い電子系化合物であるCe115系に関して、重い電子系超伝導体と通常金属の積層構造(CeCoIn5/YbCoIn5)、重い電子系反強磁性体と通常金属の積層構造(CeRhIn5/YbRhIn5)、重い電子系超伝導体のトリコロール格子(YbRhIn5/CeCoIn5/YbCoIn5)、更には重い電子系超伝導体と重い電子系反強磁性体のハイブリッド超格子(CeCoIn5/ CeRhIn5)の作製に成功した．これらの重い電子系人工超格子について、その電子状態および超伝導特性に関する詳細を調べている．

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

様々な人工超格子の作製に取り組み、特に、層状重い電子系化合物であるCe115系に関して、重い電子系超伝導体と通常金属の積層構造(CeCoIn5/YbCoIn5)、重い電子系反強磁性体と通常金属の積層構造(CeRhIn5/YbRhIn5)、重い電子系超伝導体のトリコロール格子(YbRhIn5/CeCoIn5/YbCoIn5)、更には重い電子系超伝導体と重い電子系反強磁性体のハイブリッド超格子(CeCoIn5/ CeRhIn5)の作製に成功した．現在、各々の人工超格子について電子状態および超伝導特性について研究を進めている．これに加えて、核磁気共鳴実験グループやTHz応答研究グループとの共同研究により、人工超格子における異常な電子状態の研究に取り組み、バルク物質にはない興味深い電子状態の研究が着実に進んでいる．

Strategy for Future Research Activity

当該研究の重要なプロジェクトの一つである分子線エピタキシー(MBE)装置と走査トンネル顕微鏡(STM)を結合させた装置によって、重い電子系化合物の薄膜において初めてのトンネル分光測定を実現する．これによりバルク劈開面よりも詳細なトポグラフ像とスペクトラム観測を行い、近藤混成ギャップと超伝導ギャップの明瞭な観測を実現する．更に、MBE法の特徴を活かしてCeCoIn5に微量なLa元素を不純物として人工的に導入し、制御された不純物周りでの近藤ホールの観測を行なう．

Research Products

• [Int'l Joint Research] Karlsruhe Institute of Technology(ドイツ)
  • Country Name: GERMANY
  • Counterpart Institution: Karlsruhe Institute of Technology
• [Int'l Joint Research] Bristol University/University of Oxford(英国)
  • Country Name: UNITED KINGDOM
  • Counterpart Institution: Bristol University/University of Oxford
• [Int'l Joint Research] LNCMI-Grenoble/LNCMI-Toulouse(フランス)
  • Country Name: FRANCE
  • Counterpart Institution: LNCMI-Grenoble/LNCMI-Toulouse
• [Int'l Joint Research] Technion-Israel Institute of Technology(イスラエル)
  • Country Name: ISRAEL
  • Counterpart Institution: Technion-Israel Institute of Technology
• [Int'l Joint Research] National High Field Laboratory/Florida State University/University of Califorina San Diego(米国)
  • Country Name: U.S.A.
  • Counterpart Institution: National High Field Laboratory/Florida State University/University of Califorina San Diego
  • # of Other Institutions: 3
• [Journal Article] Fermi Surface of IrTe2 in the Valence-Bond State as Determined by Quantum Oscillations (2015)
  • Author(s): S. F. Blake, M. D. Watson, A. McCollam, S. Kasahara, R. D. Johnson, A. Narayanan, G. L. Pascut, K. Haule, V. Kiryukhin, T. Yamashita, D. Watanabe, T. Shibauchi, Y. Matsuda, and A. I. Coldea
  • Journal Title: Physical Review B Volume: 91 Pages: 121105(R)
  • DOI: http://dx.doi.org/10.1103/PhysRevB.91.121105
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Emergence of Orbital Nematicity in the Tetragonal Phase of BaFe2(As1-xPx)2 (2015)
  • Author(s): T. Iye, M.-H. Julien, H. Mayaffre, M. Horvatic, C. Berthier, K. Ishida, H. Ikeda, S. Kasahara, T. Shibauchi, and Y. Matsuda
  • Journal Title: Journal of the Physical Society of Japan Volume: 84 Pages: 043705
  • DOI: http://dx.doi.org/10.7566/JPSJ.84.043705
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Local Characterization of Superconductivity in BaFe2(As1-xPx)2 (2015)
  • Author(s): Y. Lamhot, A. Yagil, N. Shapira, S. Kasahara, T. Watashige, T. Shibauchi, Y. Matsuda, and O. M. Auslaender
  • Journal Title: Physical Review B Volume: 91 Pages: 060504(R)
  • DOI: http://dx.doi.org/10.1103/PhysRevB.91.060504
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Structural Origin of the Anomalous Temperature Dependence of the Local Magnetic Moments in the CaFe2As2 Family of Materials (2015)
  • Author(s): L. Ortenzi, H. Gretarsson, S. Kasahara, Y. Matsuda, T. Shibauchi, K. D. Finkelstein, W. Wu, S. R. Julian, Y.-J. Kim, I. I. Mazin, and L. Boeri
  • Journal Title: Physical Review Letters Volume: 114 Pages: 047001
  • DOI: http://dx.doi.org/10.1103/PhysRevLett.114.047001
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Colossal Thermomagnetic Response in the Exotic Superconductor URu2Si2 (2015)
  • Author(s): T. Yamashita, Y. Shimoyama, Y. Haga, T. D. Matsuda, E. Yamamoto, Y. Onuki, H. Sumiyoshi, S. Fujimoto, A. Levchenko, T. Shibauchi, and Y. Matsuda
  • Journal Title: Nature Physics Volume: 11 Pages: 17-20
  • DOI: 10.1038/nphys3170
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Disorder-Induced Topological Change of the Superconducting Gap Structure in Iron Pnictides (2015)
  • Author(s): Y. Mizukami, M. Konczykowski, Y. Kawamoto, S. Kurata, S. Kasahara, K. Hashimoto, V. Mishra, A. Kreisel, Y. Wang, P. J. Hirschfeld, Y. Matsuda, and T. Shibauchi
  • Journal Title: Nature Communications Volume: 5 Pages: 5657
  • DOI: 10.1038/ncomms6657
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Anomalous Critical Fields in Quantum Critical Superconductors (2014)
  • Author(s): C. Putzke, P. Walmsley, J. D. Fletcher, L. Malone, D. Vignolles, C. Proust, S. Badoux, P. See, H. E. Beere, D. A. Ritchie, S. Kasahara, Y. Mizukami, T. Shibauchi, Y. Matsuda, and A. Carrington
  • Journal Title: Nature Communications Volume: 5 Pages: 5679
  • DOI: doi:10.1038/ncomms6679
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Anisotropy of the Superconducting Gap in the Iron-Based Superconductor BaFe2(As1-xPx)2 (2014)
  • Author(s): T. Yoshida, S. Ideta, T. Shimojima, W. Malaeb, K. Shinada, H. Suzuki, I. Nishi, A. Fujimori, K. Ishizaka, S. Shin, Y. Nakashima, H. Anzai, M. Arita, A. Ino, H. Namatame, M. Taniguchi, H. Kumigashira, K. Ono, S. Kasahara, T. Shibauchi, T. Terashima, Y. Matsuda, et al.
  • Journal Title: Scientific Reports Volume: 4 Pages: 7292
  • DOI: 10.1038/srep07292
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Field-Induced Superconducting Phase of FeSe in the BCS-BEC Cross-over (2014)
  • Author(s): S. Kasahara, T. Watashige, T. Hanaguri, Y. Kohsaka, T. Yamashita, Y. Shimoyama, Y. Mizukami, R. Endo, H. Ikeda, K. Aoyama, T. Terashima, S. Uji, T. Wolf, H. v. Löhneysen, T. Shibauchi, and Y. Matsuda
  • Journal Title: Proceedings of the National Academy of Sciences of the United States of America Volume: 111 Pages: 16309-16313
  • DOI: 10.1073/pnas.1413477111
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Anomalous Fermi Surface in FeSe Seen by Shubnikov-de Haas Oscillation Measurements (2014)
  • Author(s): T. Terashima, N. Kikugawa, A. Kiswandhi, E.-S. Choi, J. S. Brooks, S. Kasahara, T. Watashige, H. Ikeda, T. Shibauchi, Y. Matsuda, T. Wolf, A. E. Bohmer, F. Hardy, C. Meingast, H. v. Löhneysen, and S. Uji
  • Journal Title: Physical Review B Volume: 90 Pages: 144517
  • DOI: http://dx.doi.org/10.1103/PhysRevB.90.144517
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Imaging the two-component nature of Dirac–Landau levels in the topological surface state of Bi2Se3 (2014)
  • Author(s): Ying-Shuang Fu, M. Kawamura, K. Igarashi, H. Takagi, T. Hanaguri and T. Sasagawa
  • Journal Title: Nature Physics Volume: 10 Pages: 815-819
  • DOI: http://dx.doi.org/10.1103/PhysRevB.90.014503
  • Int'l Joint Research
• [Journal Article] Infrared Pseudogap in Cuprate and Pnictide High-Temperature Superconductors (2014)
  • Author(s): S. J. Moon, Y. S. Lee, A. A. Schafgans, A. V. Chubukov, S. Kasahara, T. Shibauchi, T. Terashima, Y. Matsuda, M. A. Tanatar, R. Prozorov, A. Thaler, P. C. Canfield, S. L. Bud'ko, A. S. Sefat, D. Mandrus, K. Segawa, Y. Ando, D. N. Basov
  • Journal Title: Physical Review B Volume: 90 Pages: 014503
  • DOI: doi:10.1038/ncomms5188
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Direct observation of lattice symmetry breaking at the hidden-order transition in URu2Si2 (2014)
  • Author(s): S. Tonegawa, S. Kasahara, T. Fukuda, K. Sugimoto, N. Yasuda, Y. Tsuruhara, D. Watanabe, Y. Mizukami, Y. Haga, T. D. Matsuda, E. Yamamoto, Y. Onuki, H. Ikeda, Y. Matsuda, T. Shibauchi
  • Journal Title: Nature Communications Volume: 5 Pages: 4188
  • DOI: doi:10.1038/ncomms5188
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Controllable Rashba Spin-Orbit Interaction in Artificially Engineered Superlattices Involving the Heavy-Fermion Superconductor CeCoIn5 (2014)
  • Author(s): M. Shimozawa, S. K. Goh, R. Endo, R. Kobayashi, T. Watashige, Y. Mizukami, H. Ikeda, H. Shishido, Y. Yanase, T. Terashima, T. Shibauchi, Y. Matsuda
  • Journal Title: Physical Review Letters Volume: 112 Pages: 156404
  • DOI: http://dx.doi.org/10.1103/PhysRevLett.112.156404
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Broken Symmetries in URu2Si2 (2014)
  • Author(s): T. Shibauchi, H. Ikeda, and Y. Matsuda
  • Journal Title: Philosophical Magazine Volume: 94 Pages: 3747-3759
  • DOI: 10.1080/14786435.2014.887861
  • Peer Reviewed / Acknowledgement Compliant
• [Presentation] BCS-BEC crossover in iron-based high-TC superconductors (2015)
  • Author(s): Yuji Matsuda
  • Organizer: Quantum Criticality: Heavy Fermion Systems and Beyond
  • Place of Presentation: ヒューストン（アメリカ）
  • Year and Date: 2015-03-26 – 2015-03-27
  • Int'l Joint Research / Invited
• [Presentation] 走査型トンネル分光の発展と高温超伝導 (2015)
  • Author(s): 花栗哲郎
  • Organizer: 第 62 回応用物理学会春季学術講演会
  • Place of Presentation: 東海大学（神奈川県平塚市）
  • Year and Date: 2015-03-11 – 2015-03-14
  • Invited
• [Presentation] 強相関電子系における電子ネマティック秩序 (2014)
  • Author(s): 芝内孝禎
  • Organizer: 物性研談話会
  • Place of Presentation: 東京大学物性研究所（千葉県柏市）
  • Year and Date: 2014-12-11
  • Invited
• [Presentation] Superconducting gap and quasi-particle interference in FeSe (2014)
  • Author(s): Tetsuo Hanaguri
  • Organizer: 27th International Symposium on Superconductivity
  • Place of Presentation: タワーホール船堀（東京都江戸川区）
  • Year and Date: 2014-11-25 – 2014-11-27
  • Int'l Joint Research / Invited
• [Presentation] Superconducting gap and quasi-particle interference in FeSe (2014)
  • Author(s): Tetsuo Hanaguri
  • Organizer: International Symposium on Frontier of Superconductivity Research (IV), STM on Unconventional Superconductors
  • Place of Presentation: 北京（中国）
  • Year and Date: 2014-10-23 – 2014-10-26
  • Int'l Joint Research / Invited
• [Presentation] FeSeにおけるBCS-BECクロスオーバー領域の超伝導 (2014)
  • Author(s): 笠原成
  • Organizer: 京都大学基礎物理学研究所研究会「多自由度電子状態と電子相関が生み出す新奇超伝導の物理」
  • Place of Presentation: 京都大学基礎物理学研究所（京都府京都市）
  • Year and Date: 2014-10-21 – 2014-10-22
  • Invited
• [Presentation] FeSe の準粒子干渉と超伝導ギャップ (2014)
  • Author(s): 花栗哲郎
  • Organizer: 京都大学基礎物理学研究所研究会「多自由度電子状態と電子相関が生み出す新奇超伝導の物理」
  • Place of Presentation: 京都大学基礎物理学研究所（京都府京都市）
  • Year and Date: 2014-10-21 – 2014-10-22
  • Invited
• [Presentation] Electronic states of FeSe studied by STM/STS (2014)
  • Author(s): Tetsuo Hanaguri
  • Organizer: Research Frontier of Transition-metal Compounds Opened by Advanced Spectroscopies
  • Place of Presentation: 東北大学金属材料研究所（宮城県仙台市）
  • Year and Date: 2014-09-30 – 2014-10-02
  • Int'l Joint Research / Invited
• [Presentation] Quantum Criticality and BCS-BEC Crossover in Iron-Based Superconductors (2014)
  • Author(s): Takasada Shibauchi
  • Organizer: KITP Conference on Strong Correlations and Unconventional Superconductivity: Towards a Conceptual Framework
  • Place of Presentation: サンタバーバラ（アメリカ）
  • Year and Date: 2014-09-22 – 2014-09-26
  • Int'l Joint Research / Invited
• [Presentation] STM/STS studies on topological insulators (2014)
  • Author(s): Tetsuo Hanaguri
  • Organizer: The Fall Meeting of the European Materials Research Society
  • Place of Presentation: ワルシャワ（ポーランド）
  • Year and Date: 2014-09-15 – 2014-09-18
  • Int'l Joint Research / Invited
• [Presentation] URu2Si2の隠れた秩序とエキゾチック超伝導 (2014)
  • Author(s): 芝内孝禎
  • Organizer: 日本物理学会 2014年秋季大会
  • Place of Presentation: 中部大学（愛知県春日井市）
  • Year and Date: 2014-09-07 – 2014-09-10
  • Invited
• [Presentation] Quantum Criticality in Iron Pnictide Superconductors (2014)
  • Author(s): Takasada Shibauchi
  • Organizer: 27th International Conference on Low Temperature Physics (LT27)
  • Place of Presentation: ブエノスアイレス（アルゼンチン）
  • Year and Date: 2014-08-06 – 2014-08-13
  • Int'l Joint Research / Invited
• [Presentation] Spectroscopic-imaging scanning tunneling microscopyon FeSe single crystals (2014)
  • Author(s): Tetsuo Hanaguri
  • Organizer: The Beijing International Workshop (II) on Iron-Based Superconductors
  • Place of Presentation: 北京（中国）
  • Year and Date: 2014-08-04 – 2014-08-08
  • Int'l Joint Research / Invited
• [Presentation] 反強磁性量子臨界揺らぎと超伝導 (2014)
  • Author(s): 芝内孝禎
  • Organizer: 東北大金研ワークショップ「多自由度が協奏する分子システムの科学」
  • Place of Presentation: 東北大学金属材料研究所（宮城県仙台市）
  • Year and Date: 2014-07-18 – 2014-07-20
  • Invited
• [Presentation] Lecture on Iron-based superconductors, I-III (2014)
  • Author(s): Yuji Matsuda
  • Organizer: Boulder School 2014: Modern Aspects of Superconductivity
  • Place of Presentation: ボルダー（アメリカ）
  • Year and Date: 2014-07-13 – 2014-07-20
  • Int'l Joint Research / Invited
• [Presentation] Superconductivity in FeSe with Extremely Small Fermi Energy (2014)
  • Author(s): Shigeru Kasahara
  • Organizer: Energy Materials Nanotechnology (EMN) Workshop on Iron and Iridium based Superconductivity
  • Place of Presentation: カンクン（メキシコ）
  • Year and Date: 2014-07-09 – 2014-07-12
  • Invited
• [Presentation] Quantum Criticality and Unconventional Superconductivity in Iron-Pnictides' (2014)
  • Author(s): Takasada Shibauchi
  • Organizer: Symposium on "New Horizon of Strongly Correlated Physics" (NHSCP2014)
  • Place of Presentation: 東京大学物性研究所（千葉県柏市）
  • Year and Date: 2014-06-25 – 2014-06-27
  • Int'l Joint Research / Invited
• [Presentation] Symmetry Breaking in the Hidden-Order Phase of URu2Si2 (2014)
  • Author(s): Takasada Shibauchi
  • Organizer: REIMEI Workshop on "Electronic state of URu2Si2 and related systems"
  • Place of Presentation: ＪＡＥＡ（茨城県東海村）
  • Year and Date: 2014-06-23
  • Int'l Joint Research / Invited
• [Presentation] Electronic Nematicity in Iron-Pnictide and Heavy Fermion Compound (2014)
  • Author(s): Yuji Matsuda
  • Organizer: Gordon Research Conference on “Correlated Electron Systems: Textures, Topology, and Strong Interactions”
  • Place of Presentation: サウスハドリー（アメリカ）
  • Year and Date: 2014-06-22 – 2014-06-27
  • Int'l Joint Research / Invited
• [Presentation] The Superconducting Order Parameter in Iron-Pnictides (2014)
  • Author(s): Takasada Shibauchi
  • Organizer: International Conferences on Modern Materials and Technologies (CIMTEC 2014), 7th International Conference on Science and Engineering of Novel Superconductors
  • Place of Presentation: モンテカティーニ・テルメ（イタリア）
  • Year and Date: 2014-06-16 – 2014-06-19
  • Int'l Joint Research / Invited
• [Presentation] Superconducting Gap and Quasi-Particle Interference in FeSe (2014)
  • Author(s): Tetsuo Hanaguri
  • Organizer: The 4th International Conference of Superconductivity and Magnetism
  • Place of Presentation: アンタルヤ（トルコ）
  • Year and Date: 2014-04-27 – 2014-05-02
  • Int'l Joint Research / Invited
• [Remarks] 京都大学量子凝縮物性研究室
  • URL: http://kotai2.scphys.kyoto-u.ac.jp/