空間反転対称性の破れを人工的に制御した重い電子系超伝導体の物性研究

• Project Area: Topological Quantum Phenomena in Condensed Matter with Broken Symmetries
• Project/Area Number: 25103713
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• Research Institution: The University of Tokyo (2014); Kyoto University (2013)
• Principal Investigator: 芝内 孝禎 東京大学, 新領域創成科学研究科, 教授 (00251356)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Project Status: Completed (Fiscal Year 2014)
• Budget Amount: ¥5,980,000 (Direct Cost: ¥4,600,000、Indirect Cost: ¥1,380,000); Fiscal Year 2014: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000); Fiscal Year 2013: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
• Keywords: 空間反転対称性 / エピタキシャル成長 / 重い電子系 / 非従来型超伝導 / パウリ効果 / スピン軌道相互作用 / ラッシュバ分裂 / 分子線エピタキシー

Outline of Annual Research Achievements

本研究の目的は、結晶中における空間反転対称性の破れが電子状態における特異な変化をもたらし、電子相関の強い重い電子系化合物で現れる超伝導状態にどのような影響を与えるかを実験的に明らかにすることを目的としている。平成25年度には、Ce系重い電子系超伝導体のエピタキシャル薄膜作製技術を用いて、CeCoIn5超伝導層とYbCoIn5通常金属層の超格子構造において、通常金属層の厚みに変調をかけることにより人工的に空間反転対称性の制御を行う研究を行った。その結果、変調に伴い、上部臨界磁場に異常な変化を観測し、空間反転対称性の破れの度合いを大きくすることにより、電子構造におけるラッシュバ型のスピン軌道相互作用により、超伝導特性におけるパウリ効果を人工的に制御することに成功した。
平成26年度には、この結果を受け、局所的な空間反転対称性の破れの効果が超伝導だけではなく、量子臨界性にも影響を与えるかどうかを調べるため、反強磁性体CeRhIn5をベースとする超格子構造を作製し、その磁場中での輸送現象測定から、磁場誘起の量子臨界点の現れ方に顕著な磁場方向依存性があることを明らかにした。この結果は、ラッシュ場分裂により、スピンの向きがロックされ、磁場方向により異なるパウリ効果をもたらすことを考えるとうまく説明できることがわかった。これらの結果より、超格子構造により局所的な反転対称性の破れが、強相関電子系では顕著なパウリ効果の変化をもたらすことを実験的に明らかにした。
さらに、重い電子系超伝導体URu2Si2において、この系で議論されている時間反転対称性を破るカイラル超伝導状態に関連した、異常な超伝導揺らぎによる巨大なネルンスト効果の出現を発見した。この結果は、理論的な研究により、カイラル超伝導特有のベリー位相に関する新しい揺らぎの出現を示唆するものである。

Research Progress Status

26年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

26年度が最終年度であるため、記入しない。

Research Products

• [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, A. I. Coldea
  • Journal Title: Physical Review B Volume: 91 Issue: 12 Pages: 121105-121105
  • DOI: 10.1103/physrevb.91.121105
  • Peer Reviewed
• [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 Issue: 1 Pages: 17-20
  • DOI: 10.1038/nphys3170
  • Peer Reviewed
• [Journal Article] Field-Induced Superconducting Phase of FeSe in the BCS-BEC Crossover (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. Loehneysen, T. Shibauchi, Y. Matsuda
  • Journal Title: Proceedings of the National Academy of Sciences of the United States of America Volume: 111 Issue: 46 Pages: 16309-16313
  • DOI: 10.1073/pnas.1413477111
  • Peer Reviewed / Open Access
• [Journal Article] Disorder-Induced Topological Change of the Superconducting Gap Structure in Iron Pnictides (2014)
  • 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: Nat. Commun. Volume: 5 Issue: 1 Pages: 5657-5657
  • DOI: 10.1038/ncomms6657
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Anomalous Fermi surface in FeSe seen by Shubnikov-de Haas oscillation measurements (2014)
  • Author(s): Taichi Terashima, Naoki Kikugawa, Andhika Kiswandhi, Eun-Sang Choi, James S. Brooks, Shigeru Kasahara, Tatsuya Watashige, Hiroaki Ikeda, Takasada Shibauchi, Yuji Matsuda, Thomas Wolf, Anna E. Bohmer, Frederic Hardy, Christoph Meingast, Hilbert v. Lohneysen, Michi-To Suzuki, Ryotaro Arita, Shinya Uji
  • Journal Title: Physical Review B Volume: 90 Issue: 14 Pages: 144517-144517
  • DOI: 10.1103/physrevb.90.144517
  • Peer Reviewed
• [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, and T. Shibauchi,
  • Journal Title: Nat. Commun. Volume: 5 Issue: 1 Pages: 4188-4188
  • 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 CeCoIn_5 (2014)
  • Author(s): M. Shimozawa, et al.
  • Journal Title: Physical Review Letters Volume: 112 Issue: 15 Pages: 156404-156404
  • DOI: 10.1103/physrevlett.112.156404
  • Peer Reviewed / Open Access
• [Journal Article] Pseudogap Formation above the Superconducting Dome in Iron-Pnictides (2014)
  • Author(s): T. Shimojima et al.
  • Journal Title: Phys. Rev. B Volume: 89 Issue: 32-33 Pages: 45101-45101
  • DOI: 10.1080/14786435.2014.887861
  • Peer Reviewed
• [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, and Y. Matsuda
  • Journal Title: Phys. Rev. Lett. Volume: 112
  • Peer Reviewed
• [Journal Article] Doping evolution of the quasiparticle excitations in heavily hole-doped Ba_<1-x>KxFe_2As_2 : Apossible superconducting gap with sign-reversal between hole pockets (2014)
  • Author(s): D. Watanabe, T. Yamashita, Y. Kawamoto, S. Kurata, Y. Mizukami, et al.
  • Journal Title: Physieal Review B Volume: 89 Issue: 11 Pages: 115112-115112
  • DOI: 10.1103/physrevb.89.115112
  • Peer Reviewed / Open Access
• [Presentation] Quantum criticality and BCS-BEC crossover in iron-based superconductors (2014)
  • Author(s): T. Shibauchi
  • Organizer: KITP Conference on Strong Correlations and Unconventional Superconductivity: Towards a Conceptual Framework
  • Place of Presentation: Santa Barbara, CA, USA
  • Year and Date: 2014-09-22 – 2014-09-26
  • 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 領域8シンポジウム「重い電子系化合物の新展開」
  • 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): T. Shibauchi
  • Organizer: 27th International Conference on Low Temperature Physics (LT27)
  • Place of Presentation: Buenos Aires, Argentina
  • Year and Date: 2014-08-06 – 2014-08-13
  • 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(仙台市）
  • Year and Date: 2014-07-18 – 2014-07-20
  • Invited
• [Presentation] Quantum criticality and unconventional superconductivity in iron-pnictides (2014)
  • Author(s): T. Shibauchi
  • Organizer: ISSP workshop on "New Horizon of Strongly Correlated Physics" (NHSCP2014)
  • Place of Presentation: 東京大学物性研究所(柏市）
  • Year and Date: 2014-06-25 – 2014-06-27
  • Invited
• [Presentation] Symmetry Breaking in the Hidden-Order Phase of URu2Si2 (2014)
  • Author(s): T. Shibauchi
  • Organizer: REIMEI Workshop on "Electronic state of URu2Si2 and related systems"
  • Place of Presentation: 日本原子力研究機構(東海）
  • Year and Date: 2014-06-23
  • Invited
• [Presentation] The Superconducting Order Parameter in Iron-based Superconductors (2014)
  • Author(s): T. Shibauchi
  • Organizer: International Conferences on Modern Materials and Technologies (CIMTEC 2014), 7th International Conference on Science and Engineering of Novel Superconductors
  • Place of Presentation: Montecatini Terme, Italy
  • Year and Date: 2014-06-16 – 2014-06-19
  • Invited
• [Presentation] Quantum Criticality in Iron-pnictide Superconductors (2014)
  • Author(s): T. Shibauchi
  • Organizer: RIKEN-APW joint workshop ``Highlights in condensed matter physics"
  • Place of Presentation: 和光市理化学研究所
  • Invited
• [Presentation] 電子状態相図と不純物効果 (2014)
  • Author(s): 芝内孝禎
  • Organizer: 日本物理学会第69回年次大会
  • Place of Presentation: 東海大学湘南キャンパス
  • Invited
• [Presentation] Symmetry Breaking in the Hidden-Order Phase of URu2Si2 (2013)
  • Author(s): T. Shibauchi
  • Organizer: Lorentz Center Workshop on Hidden Order, Superconductivity, and Magnetism in URu2Si2
  • Place of Presentation: Leiden, The Netherlands
  • Invited
• [Presentation] Exotic Superconductivity of Heavy Electrons in Artificial Two-Dimensional Kondo Lattices (2013)
  • Author(s): T. Shibauchi
  • Organizer: International Conference on Electron Correlation in Nanostructures (ECN-2013)
  • Place of Presentation: Yalta, Ukraine
  • Invited
• [Presentation] Electronic phase diagram of iron-pnictide superconductor BaFe2(As1-xPx)2 (2013)
  • Author(s): T. Shibauchi
  • Organizer: The IUMRS International Conference on Advanced Materials (IUMRS-ICAM2013): Advanced superconducting materials and its applications
  • Place of Presentation: Qingdao, China
  • Invited
• [Presentation] Superconducting Gap Symmetry in BaFe2As2-Based Superconductors (2013)
  • Author(s): T. Shibauchi
  • Organizer: International Workshop on Recent Developments in Fe-based high-temperature Superconductors
  • Place of Presentation: Riverhead, New York, USA
  • Invited
• [Presentation] Symmetry Breaking in the Hidden-Order Phase of URu2Si2 (2013)
  • Author(s): T. Shibauchi
  • Organizer: The International Conference on Strongly Correlated Electron Systems (SCES 2013)
  • Place of Presentation: 東京大学本郷キャンパス
  • Invited
• [Presentation] Nematic Transition and Antiferromagnetic Quantum Critical Point in BaFe2(As1-xPx)2 (2013)
  • Author(s): T. Shibauchi
  • Organizer: Spectroscopies in Novel Superconductors (SNS2013)
  • Place of Presentation: Berkeley, California, USA
  • Invited
• [Remarks] 超伝導ゆらぎによる巨大熱磁気効果の発見
  • URL: http://www.k.u-tokyo.ac.jp/info/entry/22_entry351/
• [Remarks] 鉄系高温超伝導の発現機構を解く鍵となる電子状態を解明
  • URL: http://www.k.u-tokyo.ac.jp/info/entry/22_entry350/
• [Remarks] 「ボース・アインシュタイン凝縮に最も近い超伝導状態」を発見
  • URL: http://www.k.u-tokyo.ac.jp/info/entry/22_entry344/
• [Remarks] 直接観測された物質物理学の謎「隠れた秩序」
  • URL: http://www.k.u-tokyo.ac.jp/info/entry/22_entry314/
• [Remarks] 新学術領域研究「対称性の破れた凝縮系におけるトポロジカル量子現象」メンバープロフィール
  • URL: http://www.topological-qp.jp/member/sp_profile/profile_c01_shibauchi.html
• [Remarks] 研究紹介
  • URL: http://qpm.k.u-tokyo.ac.jp/index.php?%E7%A0%94%E7%A9%B6%E7%B4%B9%E4%BB%8B