Exotic phenomena in unconventional superconductors: The role of the spin-orbit coupling and chirality of the Cooper pair

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K03826
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: Hirosaki University
• Principal Investigator: Goryo Jun 弘前大学, 理工学研究科, 教授 (70365013)
• Co-Investigator(Kenkyū-buntansha): 植木 輝 北海道大学, 理学研究院, 研究院研究員 (90828469)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: Superconductivity / Topology / Spin-orbit interaction

Outline of Final Research Achievements

In this study, we focus on the honeycomb network superconductors SrPtAs and investigate the non-trivial superconducting phenomena induced by spin-orbit interaction. Specifically, we pursue the possibility that the superconductivity in SrPtAs realizes a topological chiral d-wave pairing symmetry that breaks time-reversal symmetry. We thoroughly examine the interplay between spin-orbit interaction and chiral pairing, revealing that spontaneous magnetization can occur at the sample boundaries. This phenomenon is shown to be a universal property, occurring not only in SrPtAs but also in chiral superconducting states of spin-Hall metals, as demonstrated using another general model.

Free Research Field

凝縮系物理学理論

Academic Significance and Societal Importance of the Research Achievements

超伝導と磁性は元来相反するものと考えられてきた. しかし, 強磁性超伝導体など磁性と超伝導が共存する場合も存在し得ることが, 強相関電子系の超伝導に関する議論が発展するにつれ明らかになってきた.この問題は, クーパー対のトポロジー的性質とスピン軌道相互作用の協奏により自発磁化が発生するというものであり, 磁性の起源として新しいものである. 超伝導スピントロニクスに新たな知見を用いることとなり, 新たなデバイス開発への足掛かりともなり得る.