Novel orbital physics and mechanism of superconductivity in Fe-based superconductors

• Project/Area Number: 24340081
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Nagoya University
• Principal Investigator: Kontani Hiroshi 名古屋大学, 理学(系)研究科(研究院), 教授 (90272533)
• Co-Investigator(Kenkyū-buntansha): Matsuda Yuji 京都大学, 大学院理学研究科, 教授 (50199816)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥19,110,000 (Direct Cost: ¥14,700,000、Indirect Cost: ¥4,410,000); Fiscal Year 2014: ¥7,540,000 (Direct Cost: ¥5,800,000、Indirect Cost: ¥1,740,000); Fiscal Year 2013: ¥7,540,000 (Direct Cost: ¥5,800,000、Indirect Cost: ¥1,740,000); Fiscal Year 2012: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
• Keywords: 強相関電子系 / 鉄系超伝導体 / 銅酸化物高温超伝導体 / 軌道秩序 / 電荷秩序 / 超伝導発現機構 / フェルミ液体理論 / 揺らぎの理論 / バーテックス補正 / 軌道揺らぎ / 量子臨界現象 / 軌道自由度 / 繰り込み群 / 重い電子系 / 輸送現象 / スピン揺らぎ

Outline of Final Research Achievements

We studied (i) the origin of the C2-symmetric electronic nematic order and (ii) the mechanism of high-Tc superconductivity in Fe-based superconductors. The nematic order cannot be explained within the mean-field-type approximations. However, we revealed that the orbital order originates from the vertex correction, which represents the mode-coupling between orbital and spin fluctuations. Therefore, the nematic order in Fe-based superconductors is satisfactorily explained as the C2-symmetric electronic state due to the orbital order. By analyzing the vertex correction, the nematic order without magnetization in FeSe has been explained satisfactorily. In addition, we revealed that the orbital fluctuations give the strong pairing interaction that accounts for high-Tc superconductivity.

Research Products

• [Journal Article] Quasiparticle Interference in Fe-based Superconductors Based on a Five-Orbital Tight-Binding Model (2015)
  • Author(s): Youichi Yamakawa, Hiroshi Kontani
  • Journal Title: Phys. Rev. B Volume: 92 Issue: 4 Pages: 045124-045124
  • DOI: 10.1103/physrevb.92.045124
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Revisiting orbital-fluctuation-mediated superconductivity in LiFeAs: Nontrivial spin-orbit interaction effects on the band structure and superconducting gap function (2015)
  • Author(s): Tetsuro Saito, Youichi Yamakawa, Seiichiro Onari, and Hiroshi Kontani
  • Journal Title: Physical Review B Volume: 92 Issue: 13 Pages: 134522-134522
  • DOI: 10.1103/physrevb.92.134522
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Spin Triplet Superconductivity in Sr2RuO4 due to Orbital and Spin Fluctuations: Analyses by Two-Dimensional Renormalization Group Theory and Self-Consistent Vertex-Correction Method (2015)
  • Author(s): M. Tsuchiizu, Y. Yamakawa, Y. Ohno, S. Onari, and H. Kontani
  • Journal Title: Phys. Rev. B Volume: 91 Issue: 15 Pages: 155103-155103
  • DOI: 10.1103/physrevb.91.155103
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Spin-Fluctuation-Driven Nematic Charge-Density-Wave in Cuprate Superconductors: Impact of Aslamazov-Larkin-Type Vertex Correction (2015)
  • Author(s): Youichi Yamakawa, Hiroshi Kontani
  • Journal Title: Phys. Rev. Lett. Volume: 114 Issue: 25 Pages: 257001-257001
  • DOI: 10.1103/physrevlett.114.257001
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] High-Tc Superconductivity near the Anion Height Instability in Fe-Based Superconductors: Analysis of LaFeAsO1−xHx (2014)
  • Author(s): Seiichiro Onari, Youichi Yamakawa, and Hiroshi Kontani
  • Journal Title: Phys. Rev. Lett. Volume: 112 Issue: 18 Pages: 187001-187001
  • DOI: 10.1103/physrevlett.112.187001
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Reproduction of experimental gap structure in LiFeAs based on orbital-spin fluctuation theory: s++-wave, s±-wave, and hole-s±-wave states (2014)
  • Author(s): Tetsuro Saito, Seiichiro Onari, Youichi Yamakawa, Hiroshi Kontani, Sergey V. Borisenko, and Volodymyr B. Zabolotnyy
  • Journal Title: Phys. Rev. B Volume: 90 Issue: 3 Pages: 035104-035104
  • DOI: 10.1103/physrevb.90.035104
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Linear Response Theory for Shear Modulus $C_{66}$ and Raman Quadrupole Susceptibility: Significant Evidence for Orbital Nematic Fluctuations in Fe-Based Superconductor (2014)
  • Author(s): H. Kontani and Y. Yamakawa
  • Journal Title: Phys. Rev. Lett. Volume: 113 Issue: 4 Pages: 47001-47001
  • DOI: 10.1103/physrevlett.113.047001
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Detection of antiferromagnetic ordering in heavily doped LaFeAsO_<1-x>H_x pnictide superconductors using nuclear- magnetic-resonance techniques (2013)
  • Author(s): N. Fujiwara, S. Tsutsumi, S. Iimura, S. Matsuishi, H. Hosono, Y. Yamakawa, and H. Kontani
  • Journal Title: Physical Review Letters Volume: 111 Issue: 9 Pages: 970021-5
  • DOI: 10.1103/physrevlett.111.097002
  • NAID: 120005333784
  • Peer Reviewed
• [Journal Article] Orbital Nematic Instability in the Two-Orbital Hubbard Model: Renormalization-Group + Constrained RPA Analysis (2013)
  • Author(s): Masahisa Tsuchiizu, Yusuke Ohno, Seiichiro Onari, and Hiroshi Kontani
  • Journal Title: Phys. Rev. Lett. Volume: 111 Issue: 5 Pages: 57003-57003
  • DOI: 10.1103/physrevlett.111.057003
  • Peer Reviewed
• [Journal Article] Detection of Antiferromagnetic Ordering in Heavily Doped LaFeAsO_<1-x>H_x Pnictide Superconductors Using Nuclear-Magnetic-Resonance Techniques (2013)
  • Author(s): Naoki Fujiwara, et. al.
  • Journal Title: Phys. Rev. Lett. Volume: 111 Issue: 4 Pages: 0411061-5
  • DOI: 10.1103/physrevb.88.041106
  • Peer Reviewed
• [Journal Article] Nodal gap structure in Fe-based superconductors due to the competition Between orbital and spin fluctuations (2013)
  • Author(s): Tetsuro Saito, Seiichiro Onari, and Hiroshi Kontani
  • Journal Title: Physical Review B Volume: 88 Issue: 4 Pages: 45115-45115
  • DOI: 10.1103/physrevb.88.045115
  • Peer Reviewed
• [Journal Article] Impurity-induced electronic nematic state and C2-symmetric nanostructures in iron pnictide superconductors (2012)
  • Author(s): Yoshio Inoue, Youichi Yamakawa, and Hiroshi Kontani
  • Journal Title: Phys. Rev. B 85, (2012) Volume: 85 Issue: 22
  • DOI: 10.1103/physrevb.85.224506
  • Peer Reviewed
• [Journal Article] Effect of inelastic scattering on the nuclear magnetic relaxation rate 1/T1T in iron-based superconductors (2012)
  • Author(s): Youichi Yamakawa, Seiichiro Onari and Hiroshi Kontani
  • Journal Title: Superconductor Science and Technology Volume: 25 Issue: 8 Pages: 084006-084006
  • DOI: 10.1088/0953-2048/25/8/084006
  • Peer Reviewed
• [Journal Article] Non-Fermi-liquid transport phenomena and superconductivity driven by orbital fluctuations in iron pnictides: Analysis by fluctuation-exchange approximation (2012)
  • Author(s): Seiichiro Onari, Hiroshi Kontani
  • Journal Title: Physical Review B Volume: 85 Issue: 13
  • DOI: 10.1103/physrevb.85.134507
  • Peer Reviewed
• [Presentation] Orbital order driven by vertex corrections (2015)
  • Author(s): Hiroshi Kontani
  • Organizer: Workshop on the two-dimensional chalcogenides: exotic electronic orders, superconductivity and magnetism 2015
  • Place of Presentation: IFW Dresden, Germany
  • Year and Date: 2015-08-31
  • Int'l Joint Research / Invited
• [Presentation] Orbital order driven by vertex corrections (2015)
  • Author(s): Hiroshi Kontani
  • Organizer: SUPERSTRIPES 2015
  • Place of Presentation: Ischia, Italy
  • Year and Date: 2015-06-13
  • Int'l Joint Research / Invited
• [Presentation] Why Orbital Order and Fluctuations Originate from the Coulomb Interaction in Multiorbital Hubbard Models? (2015)
  • Author(s): Hiroshi Kontani
  • Organizer: Gordon Research Conference "Unconventional Superconductivity: Materials and Mechanisms"
  • Place of Presentation: The Chinese University of Hong Kong, Hong Kong, China
  • Year and Date: 2015-05-24
  • Int'l Joint Research / Invited
• [Presentation] Mechanism of orbital fluctuations and superconductivity in Fe‐based superconductors (2014)
  • Author(s): H. Kontani
  • Organizer: Itinerant Magnetism and Superconductivity - IMS 2014
  • Place of Presentation: Dresden, Germany
  • Year and Date: 2014-07-24
  • Invited
• [Presentation] Charge-Orbital-Spin Multimode Fluctuations due to Vertex Correction in Fe-Based Superconductors, High-Tc Cuprates, and Ruthenades (2014)
  • Author(s): H. Kontani
  • Organizer: International School , MULTI-CONDENSATES SUPERCONDUCTIVITY
  • Place of Presentation: Erice, Itary
  • Year and Date: 2014-07-21
  • Invited
• [Presentation] Orbital Fluctuation Induced Nematicity and Superconductivity (2014)
  • Author(s): H. Kontani
  • Organizer: Energy Materials Nanotechnology (EMN) Meeting
  • Place of Presentation: Cancun, Mexico
  • Year and Date: 2014-06-12
  • Invited
• [Presentation] Mechanism of orbital fluctuations and superconductivity in Fe-based superconductors (2014)
  • Author(s): H. Kontani
  • Organizer: 4th International Conference on Superconductivity and Magnetism
  • Place of Presentation: Antalya, Turkey
  • Year and Date: 2014-04-29
  • Invited
• [Presentation] C2 and C4 structure transitions and double-dome superconducting phase in LaFeAsO_{1-x}H_{x} (2013)
  • Author(s): H. Kontani
  • Organizer: Novel Superconductors and Super Materials 2013 (NS2 2013)
  • Place of Presentation: Tokyo, Japan
  • Invited
• [Presentation] Pairing mechanism and impurity effect on the superconductivity in iron-based superconductors (2013)
  • Author(s): H. Kontani
  • Organizer: Superconductivity: the Second Century
  • Place of Presentation: Stockholm, Sweden
  • Invited
• [Presentation] Analysis of superconducting gap structure in Fe-based superconductors (2013)
  • Author(s): H. Kontani
  • Organizer: IMR International Workshop "Superconductivity research advanced by new materials and spectroscopies"
  • Place of Presentation: Sendai, Japan
  • Invited
• [Presentation] Novel orbital physics and phase diagram in iron-based superconductors (2013)
  • Author(s): H. Kontani
  • Organizer: Gordon Research Conferences, “Superconductivity”
  • Place of Presentation: Les Diablerets, Switzerland
  • Invited
• [Presentation] Important roles of spin and orbital degrees of freedom in Fe-based superconductors: a unified understanding of the phase diagram (2013)
  • Author(s): H. Kontani
  • Organizer: The International Conference on Strongly Correlated Electron Systems
  • Place of Presentation: Tokyo, Japan
• [Presentation] Orbital Fluctuation Mediated Superconductivity and Structure Transition in Iron-Based Superconductors (2012)
  • Author(s): Hiroshi Kontani
  • Organizer: Materials & Mechanisms of Superconductivity Conference(M2S2012)
  • Place of Presentation: Washington, D.C, USA(招待講演)
  • Year and Date: 2012-08-01
• [Book] Transport Phenomena in Strongly Correlated Fermi Liquids (2013)
  • Author(s): Hiroshi Kontani
  • Total Pages: 185
  • Publisher: Springer-Verlag Berlin and Heidelberg GmbH & Co. K