磁気共鳴による高圧力下分子性物質新機能の探索

• Project/Area Number: 15073204
• Research Category: Grant-in-Aid for Scientific Research on Priority Areas
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• Research Institution: The University of Tokyo
• Principal Investigator: 鹿野田 一司 The University of Tokyo, 大学院・工学研究系, 教授 (20194946)
• Co-Investigator(Kenkyū-buntansha): 宮川 和也 東京大学, 大学院・工学研究系, 助教 (90302760) ; 藤山 茂樹 東京大学, 大学院・工学研究系, 研究拠点形成特任教員 (00342634)
• Project Period (FY): 2003 – 2007
• Project Status: Completed (Fiscal Year 2007)
• Budget Amount: ¥35,800,000 (Direct Cost: ¥35,800,000); Fiscal Year 2007: ¥5,300,000 (Direct Cost: ¥5,300,000); Fiscal Year 2006: ¥7,500,000 (Direct Cost: ¥7,500,000); Fiscal Year 2005: ¥11,100,000 (Direct Cost: ¥11,100,000); Fiscal Year 2004: ¥6,500,000 (Direct Cost: ¥6,500,000); Fiscal Year 2003: ¥5,400,000 (Direct Cost: ¥5,400,000)
• Keywords: 強相関電子系 / 核磁気共鳴 / 高圧 / モット絶縁体 / スピン液体 / ゼロギャップ伝導体 / 中性-イオン性転移 / 超高圧実験 / モット転移 / 強電子相関 / 異方的圧力 / ゼロギャップ半導体 / 分子性固体 / 物性実験 / 高圧力 / 磁気共鳴

Research Abstract

本課題では高圧下での分子性物質の機能性を磁気共鳴法によって探索することを目的とした。
課題遂行のため圧力の増減を任意の温度で加減できるガス圧力方式に加え、A01班の村田グループと共同研究を行い圧力媒体にダフニー7474オイルを使用し4Gpaまでの高圧、それ以上はダイヤモンドアンビル方式による圧力発生方式を導入し核磁気共鳴実験を行った。
この結果以下のことを見出した。
モット絶縁体κ-(BEDT-TTF)2Cu2(CN)3において三角格子に起因するフラストレーションによってスピン液体状態が実現していること、加えて加圧下NMR測定からスピン液体相に超伝導相が隣接していることを見出した。
擬二次元モット絶縁体κ-(BEDTT-TTF)2Cu[N(CN)2]C1において圧力をパラメータとしたモット転移近傍の相図を完成させ、特異な臨界指数をもつことを見出した。
有機伝導体θ-(BEDT-TTF)2I3は高圧下でゼロギャップ伝導体の可能性が指摘されているが、高圧下で13C NMR測定を行いスピン-格子緩和率、スピンシフトの振る舞いがゼロギャップ状態と矛盾しない結果を得た。
中性-イオン性(N-I)転移を示すDMTTF-CAのNQR測定を行い、この物質のN-I転移が量子臨界性をもつ可能性について探索した。加えて同じくN-I転移を示すTTF-CAに関してNQR測定を高圧領域まで行うことにより、従来、見つかっていないイオン性常誘電相の存在の可能性を指摘した。

Research Products

• [Journal Article] Thermodynamic Properties of a Spin 1/2 Spin-liquid State in a k-type Organic Salt (2008)
  • Author(s): S. Yamashita, Y. Nakazawa, M. Oguni, Y. Oshima, H. Nojiri, Y. Shimizu, K. Miyagawa, K. Kanoda
  • Journal Title: Nature Physics (In press)
  • Peer Reviewed
• [Journal Article] NMR Evidence for Antiferromagnetic Transition in the Single-component Molecular Conductor, [Au (tmdt)_2] at 110 K (2008)
  • Author(s): Y. Hara, K. Miyagawa, K. Kanoda, M. Shimamura, B. Zhou, A. Kobayashi, H. Kobayashi
  • Journal Title: Journal of Physical Society of Japan (in press)
  • NAID: 110006665983
  • Peer Reviewed
• [Journal Article] Neutral-ionic phase transition in DMTTF-QCl_4 investigated by ^<35>Cl NQR (2007)
  • Author(s): F. Iwase, K. Miyagawa, s. Fujiyama, K. Kanoda, S. Horiuchi, Y. Tokura
  • Journal Title: Journal Physical Society of Japan 76
  • NAID: 110006350742
  • Peer Reviewed
• [Journal Article] Neutral-Ionic Phase Transition in DMTTF-QC1_4 Investigated by 35CI NQR (2007)
  • Author(s): F. Iwasel, K. Miyagawa, S. Fujiyama, K. Kanoda, S. Horiuchi, and Y. Tokura
  • Journal Title: Journal of Physical Society of Japan 76
  • Peer Reviewed
• [Journal Article] Wigner crystallization in (DI-DCNQI)_2Ag detected by synchrotron radiation X-ray diffraction (2007)
  • Author(s): T.Kakiuchi, Y.Wakabayashi, H.Sawa, T.Itou, K.Kanoda
  • Journal Title: Physical Review Letters 98
• [Journal Article] Emergence of inhomogeneous moments from spin liquid in the triangular-lattice Mott insulator κ-(ET)_2Cu_2(CN)_3 (2006)
  • Author(s): Y. Shimizu, K. Miyagawa, K. Kanoda, M. Maesato, G. Saito
  • Journal Title: Physical Review B 73
  • Peer Reviewed
• [Journal Article] Mott-Insulator Transition in k-(ET)2X and DCNQI)2X : Two Contrasting Manifestation of Electron Correlation (2006)
  • Author(s): K. Kanoda
  • Journal Title: Journal Physical Society of Japan 75
  • Peer Reviewed
• [Journal Article] Emergence of inhomogeneous moments from spin liquid in the triangular lattice Mott insulator, κ-(ET)_2Cu_2(CN)_3 (2006)
  • Author(s): Y.Shimizu, K.Miyagawa, K.Kanoda, M.Maesato, G.Saito
  • Journal Title: Physical Review B 73
• [Journal Article] Metal-insulator transitions in κ-(ET)_2X and (DCNQI)_2M : Two contrasting manifestation of electron correlation (2006)
  • Author(s): K.Kanoda
  • Journal Title: Journal of Physical Society of Japan 75
  • NAID: 110004702297
• [Journal Article] Compensation of Local Field in Field-induced Superconductor κ-(BETS)_2FeBr_4 Observed by ^<77>Se NMR (2006)
  • Author(s): S.Fujiyama, M.Takigawa, J.Kikuchi, H-B.Cui, H.Fujiwara, H.Kobayashi
  • Journal Title: Physical Review Letters 96
• [Journal Article] Spin liquid state in κ-(BEDT-TTF)_2Cu_2(CN)_3 studied by muon spin relaxation method (2006)
  • Author(s): S.Ohira, Y.Shimizu, K.Kanoda, G.Saito
  • Journal Title: Journal of Low Temperature Physics 142 Pages: 153-158
• [Journal Article] Depressed charge gap in the triangular lattice Mott insulator, κ-(ET)_2Cu_2(CN)_3 (2006)
  • Author(s): I.Kezsmarki, Y.Shimizu, G.Mihaly, Y.Tokura, K.Kanoda, G.Saito
  • Journal Title: Physical Review B 74
• [Journal Article] Redistribution of electronic charges in spin-Peierls state in (TMTTF)_2AsF_6 observed by ^<13>C NMR (2006)
  • Author(s): S.Fujiyama
  • Journal Title: Journal of Physical Society of Japan. 75 Pages: 14705-14705
  • NAID: 110003482837
• [Journal Article] Mott transition from a spin liquid to a fermi liquid in the spin-frustrated organic conductor κ-(ET)_2Cu_2(CN)_3 (2005)
  • Author(s): Y. Kurosaki, Y. Shimizu, K. Miyagawa, K. Kanoda, G. Saito
  • Journal Title: Physical Review Letters 95
  • Peer Reviewed
• [Journal Article] Unconventional critical behavior in a quasi-two-dimensional organic conductor (2005)
  • Author(s): F. Kagawa, K. Miyagawa, K. Kanoda
  • Journal Title: Nature 436 Pages: 534-537
  • Peer Reviewed
• [Journal Article] The origin of the phase separation in partially deuterated κ-(ET)_2Cu[N(CN)_2]Br studied by infrared magneto-optical imaging spectroscopy (2005)
  • Author(s): T. Nishi, S. Kimura, T. Takahashi, T. Ito, HJ. Im, YS. Kwon, K. Miyagawa, H. Taniguchi, A. Kawamoto, K. Kanoda
  • Journal Title: Solid State Communication 134 Pages: 189-193
  • Peer Reviewed
• [Journal Article] Charge ordering and frustration in organic conductors (2005)
  • Author(s): K.Kanoda
  • Journal Title: JOURNAL DE PHYSIQUE IV 131 Pages: 21-21
• [Journal Article] Nuclear spin-lattice relaxation in κ-(BETS)_2FeBr_4 (2005)
  • Author(s): S.Fujiyama
  • Journal Title: Synthetic Metals 154 Pages: 253-253
• [Journal Article] ^<13>C NMR spectral study of Q1D organic conductor (TMTTF)_2AsF_6 (2005)
  • Author(s): S.Fujiyama
  • Journal Title: JOURNAL DE PHYSIQUE IV 131 Pages: 33-33
• [Journal Article] Mott transition from a spin liquid to a fermi liquid in the spin-frustrated organic conductor κ-(BEDT-TTF)_2Cu_2(CN)_3 (2005)
  • Author(s): Y.Kurosaki
  • Journal Title: Physical Review Letters 95
• [Journal Article] Unconventional critical behaviour in a quasi-two-dimensional organic conductor (2005)
  • Author(s): F.Kagawa
  • Journal Title: Nature 436 Pages: 534-537
• [Journal Article] Magnetic-field-induced Mott transition in a quasi-two-dimensional organic conductor (2005)
  • Author(s): F.Kagawa, T.Itou, K.Miyagawa, K.Kanoda
  • Journal Title: PHYSICAL REVIEW LETTERS 93・12
• [Journal Article] 有機伝導体の物質探索と物性研究 (2005)
  • Author(s): 鹿野田 一司
  • Journal Title: 日本応用物理学会誌「応用物理」 94 Pages: 9-16
• [Journal Article] NMR studies on two-dimensional molecular conductors and superconductors: Mott transition in κ-(BEDT-TTF)_2X (2004)
  • Author(s): K. Miyagawa, A. Kawamoto, K. Kanoda
  • Journal Title: Chemical Review 104 Pages: 5635-5653
  • Peer Reviewed
• [Journal Article] Magnetic-field-induced Mott transition in a quasi-two-dimensional organic conductor (2004)
  • Author(s): F. Kagawa, T. Itou, K. Miyagawa, K. Kanoda
  • Journal Title: Physical Review Letters 93
  • Peer Reviewed
• [Journal Article] Transport criticality of the first-order Mott transition in the quasi-two-dimensional organic conductor K-(BEDT-TTF)_2Cu[N(CN)2]Cl (2004)
  • Author(s): F. Kagawa, T. Itou, K. Miyagawa, K. Kanoda
  • Journal Title: Physical Review B 69
  • Peer Reviewed
• [Journal Article] Collapse of charge order in a quasi-one-dimensional organic conductor with a quarter-filled band (2004)
  • Author(s): T.Itou, K.Kanoda, K.Murata, T.Matsumoto, K.Hiraki, T.Takahashi
  • Journal Title: SPHYSICAL REVIEW LETTERS 93・21
• [Journal Article] NMR studies on two-dimensional molecular conductors and superconductors : Mott transition in κ-(BEDT-TTF)(2)X (2004)
  • Author(s): K.Miyagawa, K.Kanoda, A.Kawamoto
  • Journal Title: CHEMICAL REVIEWS 104・11 Pages: 5635-5653
• [Journal Article] Spin liquid state in an organic Mott insulator with a triangular lattice (2003)
  • Author(s): Y. Shimizu, K. Miyagawa, K. Kanoda, M. Maesato, G. Saito
  • Journal Title: Physical Eeview Letters 91
  • Peer Reviewed
• [Presentation] ^<13>C NMR studies on the organic zero-gap system, θ-(BEDT-TTF)2 I 3 under pressure (2008)
  • Author(s): K. Miyagawa, M. Hirayama, M. Tamura, K. Kanoda
  • Organizer: 2008 APS March Meeting
  • Place of Presentation: ニューオリンズ(アメリカ)
  • Year and Date: 2008-03-11
• [Presentation] θ-(BEDT-TTF)_2I_3の高圧力下NMR: ゼロギャップ状態の可能性 (2007)
  • Author(s): 宮川 和也
  • Organizer: 「ゼロギャップ 電気伝導体」 研究会
  • Place of Presentation: 東邦大学(千葉県)
  • Year and Date: 2007-07-30
• [Presentation] Superconductivity in Organic materials (2007)
  • Author(s): K. Kanoda
  • Organizer: Cargese Summer School 2007
  • Place of Presentation: Cargese, France
  • Year and Date: 2007-07-24
• [Presentation] Spin liquid and Mott transition in layered organics (2007)
  • Author(s): K. Kanoda
  • Organizer: The International Conference on Strongly Correlated Electron Systems
  • Place of Presentation: Houston, Texas, USA
  • Year and Date: 2007-05-15
• [Presentation] Mott Physics on Triangular Lattice (2006)
  • Author(s): K. Kanoda
  • Organizer: International Conference on Magnetism (ICM2006, Kyoto)
  • Place of Presentation: 京都(日本)
  • Year and Date: 2006-08-24
• [Presentation] ET compounds ; playground of spin and charge with frustration (2006)
  • Author(s): K. Kanoda
  • Organizer: The International Conference on Science andTechnology of SyntheticMetals (ICSM2006)
  • Place of Presentation: ダブリン(アメリカ)
  • Year and Date: 2006-07-06
• [Presentation] Mott criticality, spin liquid and superconductivity (2005)
  • Author(s): K. Kanoda, Y. Shimizu, F. Kagawa, Y. Kurosaki, H. Kasahara, K. Miyagawa, M. Maesato, G. Saito
  • Organizer: The 24th International Conference on Low Temperature Physics
  • Place of Presentation: オーランド(アメリカ)
  • Year and Date: 2005-08-13
• [Publications] T.Itou, K.Miyagawa, K.Kanoda, K.Hiraki, T.Takahashi: "Electronic state of (DI-DCNQI)_2Ag under ambient and applied pressures"Synthetic Metals. 133. 293-294 (2003)
• [Publications] 妹尾 仁嗣, 鹿野田 一司, 福山秀敏: "分子性結晶における電荷秩序"日本物理学会誌. 58. 801-808 (2003)
• [Publications] F.Kagawa, T.Itou, K.Miyagawa, K.Kanoda: "Transport criticality of the first-order Mott transition in a quasi-two-dimensional organic conductor, κ-(BEDT-TTF)_2Cu[N(CN)_2]Cl"Physical Review B. 69. 064511-1-064511-5 (2004)