サイクロトロン共鳴による「隠れた秩序」相における電子構造の解明

• Project Area: Emergence of Heavy Electrons and Their Ordering
• Project/Area Number: 23102713
• 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: Kyoto University
• Principal Investigator: 芝内 孝禎 京都大学, 理学(系)研究科(研究院), 准教授 (00251356)
• Project Period (FY): 2011-04-01 – 2013-03-31
• Project Status: Completed (Fiscal Year 2012)
• Budget Amount: ¥7,800,000 (Direct Cost: ¥6,000,000、Indirect Cost: ¥1,800,000); Fiscal Year 2012: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000); Fiscal Year 2011: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
• Keywords: 対称性の破れ / ネマティック秩序 / 磁場侵入長 / 量子臨界点 / フェルミ面 / 有効質量 / マイクロ波吸収 / 回転対称性の破れ / 2次相転移 / 強相関電子系

Outline of Annual Research Achievements

本研究では、重い電子系化合物の電子状態をマイクロ波を用いた低温測定により調べた。

1つめの成果として、URu2Si2の「隠れた秩序」相におけるフェルミ面の情報をサイクロトロン共鳴により明らかにした。磁場中の20-60GHz帯マイクロ波吸収測定においてサイクロトロン共鳴を観測し、26年間の謎であった「隠れた秩序」相のフェルミ面の主な構造の同定に成功した。ここで明らかになったのは、、最も信号の強い共鳴を与えるαバンドとよばれるホール面で、バンド計算や量子振動の測定からは明らかにされていなかった有効質量の分裂を発見し、[110]方向にホットスポットを持つことを強く示唆する結果を得た。この結果は、「隠れた秩序」相において正方晶の面内4回対称性を破る電子構造となっていることを示しており、「隠れた秩序」の理解が格段に進むことが期待される。
2つめはマイクロ波を用いた超伝導体の磁場侵入長測定を様々な強相関電子系において行った。特に重い電子系超伝導体の中でも反強磁性量子臨界点に近いことが知られているCeCoIn5およびCe2PdIn8の単結晶試料において、低温で磁場侵入長がともに温度の3/2乗に比例するという特異な振る舞いを示すことが明らかとなった。この温度依存性はこの系で期待されるｄ波超伝導の温度に比例する振る舞いとは異なっており、量子臨界性により超伝導電子の有効質量が波数空間に強く依存していることを示唆している。さらに同様な測定を鉄系超伝導体 BaFe2(As,P)2について行ったところ、量子臨界点近傍で同様な異常を示すとともに、絶対零度における磁場侵入長の値が鋭いピーク構造を持つことを明らかにした。この結果は、超伝導ドームの内部の絶対零度において臨界的な揺らぎが存在していることを実験的にはじめて直接示したものであり、反強磁性量子臨界点が超伝導状態内に存在することを示すものである。

Research Progress Status

24年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

24年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] Terahertz Conductivity of the Heavy-Fermion State in CeCoIn5 (2013)
  • Author(s): M. Scheffler
  • Journal Title: J. Phys. Soc. Jpn. Volume: 82 Issue: 4 Pages: 43712-43712
  • DOI: 10.7566/jpsj.82.043712
  • Peer Reviewed
• [Journal Article] Disorder, critical currents, and vortex pinning energies in isovalently substituted BaFe2(As1－xPx)2 (2013)
  • Author(s): S. Demirdis
  • Journal Title: Phys. Rev. B Volume: 87 Issue: 9 Pages: 94506-94506
  • DOI: 10.1103/physrevb.87.094506
  • Peer Reviewed
• [Journal Article] Interplane resistivity of isovalent doped BaFe2(As1－xPx)2 (2013)
  • Author(s): M. A. Tanatar
  • Journal Title: Phys. Rev. B Volume: 87 Issue: 10 Pages: 104506-104506
  • DOI: 10.1103/physrevb.87.104506
  • Peer Reviewed
• [Journal Article] Anomalous superfluid density in quantum critical superconductors (2013)
  • Author(s): K. Hashimoto, Y. Mizukami, et al.
  • Journal Title: Proceedings of the National Academy of Sciences Volume: 110 Issue: 9 Pages: 3293-3297
  • DOI: 10.1073/pnas.1221976110
  • Peer Reviewed
• [Journal Article] Strong suppression of superconductivity by divalent ytterbium Kondo holes in CeCoIn5 (2012)
  • Author(s): M. Shimozawa, et al.
  • Journal Title: Physical Review B Volume: 86 Issue: 14 Pages: 144526-144526
  • DOI: 10.1103/physrevb.86.144526
  • Peer Reviewed
• [Journal Article] Anomalous upper critical field in CeCoIn5/YbCoIn5 superlattices with a Rashba-type heavy fermion interface (2012)
  • Author(s): S. K. Goh, et al.
  • Journal Title: Physical Review Letter Volume: 109 Issue: 15 Pages: 157006-15
  • DOI: 10.1103/physrevlett.109.157006
  • Peer Reviewed
• [Journal Article] Novel Pauli-paramagnetic quantum phase in a Mott insulator (2012)
  • Author(s): D. Watanabe, et al.
  • Journal Title: Nature Communications Volume: 3 Issue: 1 Pages: 10901-6
  • DOI: 10.1038/ncomms2082
  • Peer Reviewed
• [Journal Article] Thermodynamic phase diagram, phase competition, and uniaxial pressure effects in BaFe2(As1-xPx)2 studied by thermal expansion (2012)
  • Author(s): A. E. Bohmer
  • Journal Title: Phys. Rev. B Volume: 86 Issue: 9 Pages: 94521-94521
  • DOI: 10.1103/physrevb.86.094521
  • Peer Reviewed
• [Journal Article] Octet-Line Node Structure of Superconducting Order Parameter in KFe2As2 (2012)
  • Author(s): K. Okazaki
  • Journal Title: Science Volume: 337 Issue: 6100 Pages: 1314-1317
  • DOI: 10.1126/science.1222793
  • Peer Reviewed
• [Journal Article] Cyclotron Resonance in the Hidden-Order Phase of URu2Si2 (2012)
  • Author(s): S. Tonegawa, et al.
  • Journal Title: Physcal Review Letters Volume: 109 Issue: 3 Pages: 36401-36401
  • DOI: 10.1103/physrevlett.109.036401
  • Peer Reviewed
• [Journal Article] Infrared Measurement of the Pseudogap of P-Doped and Co-Doped High-Temperature BaFe2As2 Superconductors (2012)
  • Author(s): S. J. Moon
  • Journal Title: Phys. Rev. Lett. Volume: 109 Issue: 2 Pages: 27006-27006
  • DOI: 10.1103/physrevlett.109.027006
  • Peer Reviewed
• [Journal Article] A Sharp Peak of the Zero-Temperature Penetration Depth at Optimal Composition in BaFe_2(As_<1-x>P_x)_2 (2012)
  • Author(s): K. Hashimoto, K. Cho, T. Shibauchi, S. Kasahara, Y. Mizukami, et al.
  • Journal Title: Science Volume: 336 Issue: 6088 Pages: 1554-1557
  • DOI: 10.1126/science.1219821
  • Peer Reviewed
• [Journal Article] Electronic nematicity above the structural and superconducting transition in BaFe2 (As1-xPx)2 (2012)
  • Author(s): S. Kasahara, et al.
  • Journal Title: Nature Volume: 486 Issue: 7403 Pages: 382-385
  • DOI: 10.1038/nature11178
  • Peer Reviewed
• [Journal Article] Emergent Rank-5 `Nematic' Order in Uru_2Si_2 (2012)
  • Author(s): H. Ikeda, M.-T. Suzuki, R. Arita, T. Takimoto, T. Shibauchi, and Y. Matsuda
  • Journal Title: Nature Physics Volume: 8 Issue: 7 Pages: 528-533
  • DOI: 10.1038/nphys2330
  • Peer Reviewed
• [Journal Article] Gradual suppression of antiferromagnetism in BaFe_2(As_<1-x>P_x)_2 : Zero-temperature evidence for a quantum critical point (2012)
  • Author(s): T. Iye, et al.,
  • Journal Title: Physical Review B Volume: 85 Issue: 18 Pages: 184505-184505
  • DOI: 10.1103/physrevb.85.184505
  • Peer Reviewed
• [Journal Article] Contrasts in electron correlations and inelastic scattering between LiFeP and LiFeAs revealed by charge transport (2012)
  • Author(s): S.Kasahara, et al
  • Journal Title: Physical Review B Volume: 85 Issue: 6 Pages: 60503-6057
  • DOI: 10.1103/physrevb.85.060503
  • Peer Reviewed
• [Journal Article] Microscopic Evidence of Direct Coupling between Magnetic and Superconducting Order Parameters in BaFe_2 (As_<1-x>P_x)_2 (2012)
  • Author(s): T.Iye, et al.
  • Journal Title: Journal of the Physical Society of Japan Volume: 81 Issue: 3 Pages: 33701-33701
  • DOI: 10.1143/jpsj.81.033701
  • Peer Reviewed
• [Journal Article] Nodal versus Nodeless Behaviors of the Order Parameters of LiFeP and LiFeAs Superconductors from Magnetic Penetrat ion-Depth Measurements (2012)
  • Author(s): K.Hashimoto, et al
  • Journal Title: Physical Review Letters Volume: 108 Issue: 4 Pages: 47003-47007
  • DOI: 10.1103/physrevlett.108.047003
  • Peer Reviewed
• [Journal Article] de Haas-van Alphen Study of the Fermi Surfaces of Superconducting LiFeP and LiFeAs (2012)
  • Author(s): C. Putzke
  • Journal Title: Phys. Rev. Lett. Volume: 108 Issue: 4 Pages: 47002-47002
  • DOI: 10.1103/physrevlett.108.047002
  • Peer Reviewed
• [Journal Article] Volovik effect in a highly anisotropic multiband superconductor : Experiment and theory (2011)
  • Author(s): Y.Wang, Y.Matsuda, 他8名
  • Journal Title: Phys.Rev.B (Editors' suggestion) Volume: 84 Issue: 18 Pages: 184-524
  • DOI: 10.1103/physrevb.84.184524
  • Peer Reviewed
• [Journal Article] Extremely strong-coupling superconductivity in artificial two-dimensional Kondo lattices (2011)
  • Author(s): Yuta Mizukami, et al
  • Journal Title: Nature Physics Volume: 7 Issue: 11 Pages: 849-853
  • DOI: 10.1038/nphys2112
  • Peer Reviewed
• [Journal Article] Nodal Gap Structure of Superconducting BaFe2(Asl-xPx)2 from Angle-Resolved Thermal Conductivity in a Magnetic Field (2011)
  • Author(s): M.Yamashita, et al
  • Journal Title: Physical Review B Volume: 84 Issue: 6 Pages: 60507-60510
  • DOI: 10.1103/physrevb.84.060507
  • Peer Reviewed
• [Journal Article] Nesting of electron and hole Fermi surfaces in nonsuperconducting BaFe_2P_2 (2011)
  • Author(s): B.J.Arnold, Y.Matsuda, 他5名
  • Journal Title: Phys.Rev.B Volume: 83 Issue: 22 Pages: 220504-220504
  • DOI: 10.1103/physrevb.83.220504
  • Peer Reviewed
• [Journal Article] Specific heat discontinuity, ΔC, at Tc in BaFe_2(As_<0.7>P_<0.3>)_2-consistent with unconventional superconductivity (2011)
  • Author(s): J.S.Kim, Y.Matsuda, 他4名
  • Journal Title: J.Phys. : Condens.Matter Volume: 23 Issue: 22 Pages: 222201-222201
  • DOI: 10.1088/0953-8984/23/22/222201
  • Peer Reviewed
• [Journal Article] Orbital-Independent Superconducting Gaps in Iron-Pnictides (2011)
  • Author(s): T.Shimojima, Y.Matsuda, 他18名
  • Journal Title: Science Volume: 332 Issue: 6029 Pages: 564-567
  • DOI: 10.1126/science.1202150
  • Peer Reviewed
• [Presentation] 鉄系、銅系超伝導の実験 (2013)
  • Author(s): 芝内孝禎
  • Organizer: 日本物理学会第68回年次大会
  • Place of Presentation: 広島大学東広島キャンパス
  • Year and Date: 2013-03-26
  • Invited
• [Presentation] Symmetry Breaking in the Hidden-Order Phase of URu2Si2 (2013)
  • Author(s): Takasada Shibauchi
  • Organizer: The March Meeting of the American Physical Society
  • Place of Presentation: Baltimore, MD, USA
  • Year and Date: 2013-03-18
  • Invited
• [Presentation] Antiferromagnetic Quantum Critical Point and Nematic Transition in BaFe2(As1-xPx)2 (2012)
  • Author(s): Takasada Shibauchi
  • Organizer: International Symposium on Superconductibity 2012 (ISS2012)
  • Place of Presentation: Funabori, Tokyo
  • Year and Date: 2012-12-03
  • Invited
• [Presentation] Quantum Critical Phenomena in Strongly Correlated Electron Systems (2012)
  • Author(s): Takasada Shibauchi
  • Organizer: Summit of Material Science 2012 (SMS2012)
  • Place of Presentation: Tohoku University, Sendai
  • Year and Date: 2012-11-28
  • Invited
• [Presentation] 鉄ヒ素系超伝導体の隠れた量子臨界点とネマティック相転移 (2012)
  • Author(s): 芝内孝禎
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 横浜国立大学
  • Year and Date: 2012-09-18
  • Invited
• [Presentation] Exotic Superconductivity of Heavy Electrons in Artificial Two-Dimensional Kondo Lattices (2012)
  • Author(s): Takasada Shibauchi
  • Organizer: International Conference on Quantum Criticality and Novel Phases (QCNP)
  • Place of Presentation: Dresden, Germany
  • Year and Date: 2012-08-27
  • Invited
• [Presentation] Nematic Transition and Antiferromagnetic Quantum Critical Point in BaFe2(As,P)2 (2012)
  • Author(s): Takasada Shibauchi
  • Organizer: Innovations in Strongly Correlated Electrons Workshop
  • Place of Presentation: Trieste, Italy
  • Year and Date: 2012-08-13
  • Invited
• [Presentation] Nematic Transition and Antiferromagnetic Quantum Critical Point in BaFe2(As,P)2 (2012)
  • Author(s): Takasada Shibauchi
  • Organizer: Second Joint Super‐PIRE REIMEI Workshop
  • Place of Presentation: Bethesda, MD, USA
  • Year and Date: 2012-08-03
  • Invited
• [Presentation] Quantum Critical Point Hidden beneath the Superconducting Dome of BaFe2(As,P)2 (2012)
  • Author(s): Takasada Shibauchi
  • Organizer: International Conference on Materials and Mechanisms of Superconductivity (M2S 2012)
  • Place of Presentation: Washington DC, USA
  • Year and Date: 2012-07-30
  • Invited
• [Presentation] Exotic Superconductivity of Heavy Electrons in Artificial Two-Dimensional Kondo Lattices (2012)
  • Author(s): Takasada Shibauchi
  • Organizer: The 19th International Conference on Magnetism (ICM2012) with Strongly Correlated Electron Systems (SCES)
  • Place of Presentation: Busan, Korea
  • Year and Date: 2012-07-08
  • Invited
• [Presentation] Symmetry Breaking in the Hidden Order Phase of URu2Si2 (2012)
  • Author(s): Takasada Shibauchi
  • Organizer: The 4th International Workshop on the Dual Nature of f-electrons
  • Place of Presentation: Himeji, Japan
  • Year and Date: 2012-07-04
  • Invited
• [Presentation] Exotic Superconductivity of Heavy Electrons in Artificial Two-Dimensional Kondo Lattices (2012)
  • Author(s): Takasada Shibauchi
  • Organizer: Collaborative Conference on Materials Research (CCMR2012)
  • Place of Presentation: Seoul, Korea
  • Year and Date: 2012-06-25
  • Invited
• [Presentation] Symmetry Breaking in the Hidden Order Phase of URu2Si2 (2012)
  • Author(s): Takasada Shibauchi
  • Organizer: International Conference on Superconductivity and Magnetism (ICSM2012)
  • Place of Presentation: Istanbul, Turkey
  • Year and Date: 2012-04-29
  • Invited
• [Presentation] BaFe2(As1-xPx)2の超伝導ドーム内に隠れた量子臨界点 (2012)
  • Author(s): 芝内孝禎
  • Organizer: 基研研究会「鉄系高温超伝導の物理 ～スピン・軌道・格子～」
  • Place of Presentation: 京都大学基礎物理学研究所
  • Invited
• [Presentation] Symmetry Breaking in the Hidden Order Phase of URu2Si2 (2012)
  • Author(s): T.Shibauchi
  • Organizer: UK-Japan workshop
  • Place of Presentation: 東京大学(招待講演)
• [Presentation] URu2Si2の隠れた秩序--フェルミ面における回転対称性の破れ (2012)
  • Author(s): 芝内孝禎
  • Organizer: 新学術領域研究「重い電子系の形成と秩序化」ワークショップ～超伝導、多極子の物理における最近の話題～
  • Place of Presentation: 東京大学物性研究所(招待講演)
• [Presentation] Quantum Criticality and Superconducting Gap Structure in BaFe2(As1-xPx)2 (2011)
  • Author(s): T.Shibauchi
  • Organizer: 26th International Conference on Low Temperature Physics (LT26)
  • Place of Presentation: Beijing, China(招待講演)
• [Presentation] Quantum Criticality and Superconducting Gap Structure in Iron-Pnictide Superconductors (2011)
  • Author(s): T.Shibauchi
  • Organizer: The 13th International Workshop on Vortex Matter in Superconductors
  • Place of Presentation: Chicago, IL, USA(招待講演)
• [Presentation] Nodal s-wave superconductivity in BaFe2(As1-xPx)2 (2011)
  • Author(s): T.Shibauchi
  • Organizer: Superconductivity : 100 years young
  • Place of Presentation: Natal, Brazil(招待講演)
• [Presentation] Nodal s-wave superconductivity in BaFe2(As1-xPx)2 (2011)
  • Author(s): T.Shibauchi
  • Organizer: The workshop on Unconventional Superconductivity
  • Place of Presentation: Minneapolis, Minnesota, USA(招待講演)
• [Presentation] Non-Fermi liquid transport and non-universal gap structure in iron-based superconductors (2011)
  • Author(s): T.Shibauchi
  • Organizer: 2011 Villa Conference on Iron Pnictide Superconductors (VCIPS 2011)
  • Place of Presentation: Las Vegas, Nevada, USA(招待講演)
• [Presentation] サイクロトロン共鳴によるURu2Si2の隠れた秩序相における電子構造の決定 (2011)
  • Author(s): 芝内孝禎
  • Organizer: 新学術領域研究「重い電子系の形成と秩序化」第3回研究会
  • Place of Presentation: 東京大学物性研究所
• [Presentation] マクロ測定と超伝導～発展「トルク測定とネマティック状態」 (2011)
  • Author(s): 芝内孝禎
  • Organizer: 第2回重い電子系若手秋の学校
  • Place of Presentation: 高野山大学(招待講演)
• [Presentation] BaFe2(As,P)2における量子臨界現象 (2011)
  • Author(s): 芝内孝禎
  • Organizer: 基研研究会「鉄系高温超伝導の物理」
  • Place of Presentation: 京都大学基礎物理学研究所(招待講演)
• [Remarks] Research Highlights
  • URL: http://kotai2.scphys.kyoto-u.ac.jp/index.php?Research%20Highlights
• [Remarks] 絶対零度の量子ゆらぎにより重くなる超伝導電子－電子が特定の方向で重くなる異常な現象を発見－
  • URL: http://www.kyoto-u.ac.jp/ja/news_data/h/h1/news6/2012/130212_1.htm
• [Remarks] 超伝導物質が絶対零度で示す新しい臨界現象を発見
  • URL: http://www.kyoto-u.ac.jp/ja/news_data/h/h1/news6/2012/120622_2.htm
• [Remarks] 鉄原子を含む高温超伝導体の仕組みを解くカギ「電子のネマティック液晶状態」を発見
  • URL: http://www.kyoto-u.ac.jp/ja/news_data/h/h1/news6/2012/120621_1.htm
• [Remarks]
  • URL: http://kotai2.scphys.kyoto-u.ac.jp/index.php