Microscopic theory of spin triplet superconductivity originatedby the ferromagnetic coupling due to ring-exchange mechanism

• Project/Area Number: 18540338
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Chiba University
• Principal Investigator: OHTA Yukinori Chiba University, 大学院・理学研究科, 教授 (70168954)
• Project Period (FY): 2006 – 2008
• Project Status: Completed (Fiscal Year 2008)
• Budget Amount: ¥3,150,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥450,000); Fiscal Year 2008: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2007: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
• Keywords: 超伝導 / 磁性 / 強相関電子系 / 物性理論 / リング交換 / スピン三重項超伝導 / 交換相互作用 / 密度行列繰り込み群 / トリプレット超伝導

Research Abstract

三角格子上を運動する電子系の電子スピン間に働くリング交換機構と呼ばれる強磁性結合のミクロな機構を利用してスピン三重項超伝導を導くという新規な超伝導発現機構を提案し、その機構の実現可能性を、三角格子ハバード模型、および関連するジグザグ梯子模型に密度行列繰り込み群(DMRG)という数値的手法を適用し、詳細に検討した。その結果、幅広いパラメータと電子密度の領域に於いて、f波対称性を持つスピン三重項超伝導の発現を示唆する強い数値的証拠を得た。

Research Products

• [Journal Article] Spin and Density Excitations in theTriangular-Lattice t- J Model with Multiple-Spin Exchange Interactions : ^3He on Graphite (2009)
  • Author(s): K. Seki, T. Shirakawa and Y. Ohta
  • Journal Title: Phys. Rev B79
  • Peer Reviewed
• [Journal Article] Spin and Mass Excitations in the Doped Multiple Spin Exchange Model on aTriangular Lattice : ^3He on Graphite (2009)
  • Author(s): K.Seki, T. Shirakawa and Y. Ohta, J.Phys.
  • Journal Title: Conf. Ser 150
  • Peer Reviewed
• [Journal Article] Coexistence of Distinct ChargeFluctuations in θ-(BEDT-TTF)_2X (2008)
  • Author(s): S.Nishimoto, M. Shingai and Y. Ohta
  • Journal Title: Phys. Rev B78
  • Peer Reviewed
• [Journal Article] Charge and Spin Excitation Spectra in the One-Dimensional Hubbard Modelwith Next-Nearest-Neighbor Hopping (2008)
  • Author(s): S. Nishimoto, T. Shirakawa and Y. Ohta
  • Journal Title: Phys. Rev B77
  • Peer Reviewed
• [Journal Article] Phase Diagram of the One-DimensionalHubbard Model with Next-Nearest-Neighbor Hopping (2008)
  • Author(s): S. Nishimoto, K.Sano and Y. Ohta
  • Journal Title: Phys. Rev B77
  • Peer Reviewed
• [Journal Article] Superconductivity in a Model of Two Hubbard Chains Coupled withFerromagnetic Exchange Interaction (2008)
  • Author(s): T. Shirakawa, S. Nishimoto and Y. Ohta
  • Journal Title: Phys. Rev B77
  • Peer Reviewed
• [Journal Article] XVariational Monte Carlo Study on Superconductivity in the AnisotropicTriangular-Lattice Hubbard Models (2008)
  • Author(s): Y. Kataoka and Y. Ohta
  • Journal Title: J. Phys. Chem. Solids 69 Pages: 3330-3333
  • Peer Reviewed
• [Journal Article] Numerical Study on the AnisotropicTriangular-Lattice Hubbard Model at Quarter Filling : Charge Fluctuationswith Three-Fold Periodicity (2008)
  • Author(s): M. Shingai, S. Nishimoto and Y. Ohta
  • Journal Title: J. Phys. Cheml. Solids 69 Pages: 3382-338
  • Peer Reviewed
• [Journal Article] Charge and Spin Excitation Spectra in the One-Dimensional Hubbard Model with Next-Nearest-Neighbor Hopping (2008)
  • Author(s): S. Nishimoto, T. Shirakawa, Y. Ohta
  • Journal Title: Physical Review B 77
  • Peer Reviewed
• [Journal Article] Phase Diagram of the One-Dimensional Hubbard Model with Next-Nearest-Neighbor Hopping (2008)
  • Author(s): S. Nishimoto, K. Sano, Y. Ohta
  • Journal Title: Physical Review B 77
  • Peer Reviewed
• [Journal Article] Superconductivity in a Model of Two Hubbard Chains Coupled with Ferromagnetic Exchange Interaction (2008)
  • Author(s): T. Shirakawa, S. Nishimoto, Y. Ohta
  • Journal Title: Physical Review B 77
  • Peer Reviewed
• [Journal Article] Charge and Spin Excitation Spectra in the One-Dimensional HubbardModel with NeXt-Nearest-Neighbor Hopping (2008)
  • Author(s): S.Nishimoto, T.Shirakawa, Y.Ohta
  • Journal Title: Physical Review B 77
  • Peer Reviewed
• [Journal Article] Phase Diagram of the One-Dimensional Hubbard Model with NeXt-Nearest-Neighbor Hopping (2008)
  • Author(s): S.Nishimoto, K.Sano, Y.Ohta
  • Journal Title: Physical Review B 77
  • Peer Reviewed
• [Journal Article] Phase Separation, Spin Polarization,and Triplet Superconductivity in the Hubbard Chains Coupled with Ferromagnetic Zigzag Bonds (2007)
  • Author(s): S. Nishimoto, T. Shirakawa, and Y. Ohta
  • Journal Title: J. Mag. Mag. Mater 310 Pages: 669-671
  • Peer Reviewed
• [Journal Article] Spin-Triplet f-wave Suerconductivityin One-Dimensional Triangular-Lattice Hubbard Models (2007)
  • Author(s): Y. Ohta, T.Shirakawa, and S. Nishimoto
  • Journal Title: J. Mag.Mag. Mater 310 Pages: 578-580
  • Peer Reviewed
• [Journal Article] Spin-Triplet Superconductivity in the Double-Chain Hubbard Model with Ferromagnetic Exchange Interaction (2007)
  • Author(s): Interaction, T.Shirakawa, Y. Ohta, and S. Nishimoto
  • Journal Title: J. Mag. Mag. Mater 310 Pages: 663-665
  • Peer Reviewed
• [Journal Article] Spin-Triplet Suerconductivity in theHubbard Chains Coupled with Ferromagnetic Exchange Interaction (2007)
  • Author(s): S.Nishimoto, T. Shirakawa, and Y. Ohta
  • Journal Title: Physica C460-462 Pages: 1059-1060
  • Peer Reviewed
• [Journal Article] Spin-Triplet f-Wave Pairing in thea One-Dimensional Triangular-Lattice Hubbard Model : Possible Relevance to Superconductivity in Bechgaard Salts (2007)
  • Author(s): Y. Ohta, S. Nishimoto, and T. Shirakawa
  • Journal Title: Physica C460-462 Pages: 246-247
  • Peer Reviewed
• [Journal Article] Theoretical Study on Superconductivity in Boron-Doped Diamond (2007)
  • Author(s): T.Shirakawa, S.Horiuchi, Y.Ohta, H.Fukuyama
  • Journal Title: Joumal of the Physical Society of Japan 76
  • NAID: 110006151561
  • Peer Reviewed
• [Journal Article] Phase Separation, Spin Polarization, and Triplet Superconductivity in the Hubbard Chains Coupled with Ferromagnetic Zigzag Bonds (2007)
  • Author(s): S.Nishimoto, T.Shirakawa, Y.Ohta
  • Journal Title: Journal of Magnetism and Magnetic Materials 310 Pages: 669-671
• [Journal Article] Spin-Triplet f-Wave Superconductivity in One-Dimensional Triangular-Lattice Hubbard Models (2007)
  • Author(s): Y.Ohta, T.Shirakawa, S.Nishimoto
  • Journal Title: Journal of Magnetism and Magnetic Materials 310 Pages: 578-580
• [Journal Article] Spin-Triplet Superconductivity in the Double-Chain Hubbard Model with Ferromagnetic Exchange Interaction (2007)
  • Author(s): T.Shirakawa, Y.Ohta, S.Nishimoto
  • Journal Title: Journal of Magnetism and Magnetic Materials 310 Pages: 663-665
• [Journal Article] Theoretical Study on Superconductivity in Boron-Doped Diamond (2007)
  • Author(s): T.Shirakawa, S.Horiuchi, Y.Ohta, H.Fukuyama
  • Journal Title: Journal of the Physical Society of Japan 76 Pages: 14711-14711
  • NAID: 110006151561
• [Journal Article] Triplet Superconductivity in aTwo-Chain Hubbard Model by the Ring-Exchange Mechanism (2006)
  • Author(s): T. Shirakawa, S. Nishimoto and Y. Ohta
  • Journal Title: AIPConference Proceedings Series 850 Pages: 625-626
  • Peer Reviewed
• [Journal Article] Ring-Exchange Mechanism for Triplet Superconductivity in a Two-Chain Hubbard Model (2006)
  • Author(s): Y. Ohta, S. Nishimoto,T. Shirakawa, and Y. Yamaguchi
  • Journal Title: Physica B378-380 Pages: 439-440
  • Peer Reviewed
• [Journal Article] Ring-Exchange Mechanism for Triplet Superconductivity in a Two-ChainHubbard Model : Possible Relevance toBechgaard Salts (2006)
  • Author(s): Y. Ohta, S. Nishimoto,T. Shirakawa, and Y. Yamaguchi
  • Journal Title: Phys.Rev B72
  • Peer Reviewed
• [Journal Article] Triplet Superconductivity in a Two-Chain Hubbard Model by the Ring-Exchange Mechanism (2006)
  • Author(s): T.Shirakawa, S.Nishimoto, Y.Ohta
  • Journal Title: AIP Conference Proceedings Series 850 Pages: 625-626
• [Journal Article] Ring-Exchange Mechanism for Triplet Superconductivity in a Two? Chain Hubbard Model (2006)
  • Author(s): Y.Ohta, S.Nishimoto, T.Shirakawa, Y.Yamaguchi
  • Journal Title: Physica B 378-380 Pages: 439-440
• [Presentation] グラファイト上に吸着した3Heのスピン及び密度励起 : リング交換を含む三角格子t-J 模型の研究 (2009)
  • Author(s): 関和弘、白川知功、太田幸則
  • Organizer: 日本物理学会第64回年次大会
  • Place of Presentation: 立教大学
  • Year and Date: 2009-03-30
• [Presentation] Spin and Density Excitations in the Triangular-Lattice t-J Model with Multiple-Spin Exchange Interactions (2009)
  • Author(s): Y. Ohta
  • Organizer: International Workshop on Quantum Critical Phenomena and Novel Phases…
  • Place of Presentation: Honolulu, USA
• [Presentation] 自己エネルギー汎関数法による2次元周期アンダーソン模型の解析 (2008)
  • Author(s): 堀内 諭史, 工藤 春, 太田 幸則
  • Organizer: 日本物理学会
  • Place of Presentation: 近畿大学
  • Year and Date: 2008-03-23
• [Presentation] Phase Diagram of the One-Dimensional Hubbard Model with Next-Nearest-Neighbor Hopping (2007)
  • Author(s): 西本理、佐野和博、太田幸則
  • Organizer: 日本物理学会第62回年次大会
  • Place of Presentation: 北海道大学
  • Year and Date: 2007-09-21
• [Presentation] 異方的三角格子拡張ハバード模型における3倍周期電荷揺らぎと励起スペクトル (2007)
  • Author(s): 白川知功、新貝学、西本理、太田幸則
  • Organizer: 日本物理学会2007年春季大会
  • Place of Presentation: 鹿児島大学
  • Year and Date: 2007-03-19
• [Presentation] 変分モンテカルロ法による異方的三角格子ハバード模型の研究 (2007)
  • Author(s): 片岡祐己、太田幸則
  • Organizer: 日本物理学会2007年春季大会
  • Place of Presentation: 鹿児島大学
  • Year and Date: 2007-03-19
• [Presentation] 三鎖拡張ハバード模型の電荷秩序化と超伝導に関する弱結合理論 (2007)
  • Author(s): 中田翔、白川知功、太田幸則
  • Organizer: 日本物理学会2007年春季大会
  • Place of Presentation: 鹿児島大学
  • Year and Date: 2007-03-19
• [Presentation] 異方的三角格子系における電荷秩序の融解と異常金属相に関する数値的研究 (2006)
  • Author(s): 新貝学、白川知功、西本理、太田幸則
  • Organizer: 日本物理学会2006年秋季大会
  • Place of Presentation: 千葉大学
  • Year and Date: 2006-09-24
• [Presentation] 変分モンテカルロ法による三鎖ハバード模型の超伝導に関する研究 (2006)
  • Author(s): 片岡祐己、太田幸則
  • Organizer: 日本物理学会2006年秋季大会
  • Place of Presentation: 千葉大学
  • Year and Date: 2006-09-24
• [Presentation] 強磁性相互作用で結合した2鎖ハバード模型の超伝導の理論 (2006)
  • Author(s): 白川知功、太田幸則、西本理
  • Organizer: 日本物理学会2006年秋季大会
  • Place of Presentation: 千葉大学
  • Year and Date: 2006-09-23
• [Remarks]
  • URL: http://physics.s.chiba-u.ac.jp/ohtal/
• [Remarks]
  • URL: http://physics.s.chiba-u.ac.jp/ohtal/