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

2015 Fiscal Year Final Research Report

• 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
• 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

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.

Free Research Field

物性理論