时间:4月24日周四，14:00-16:00

地点:知新楼，7层，量子报告厅

Abstract: Due to the breaking of centrosymmetry and the effects of multi-orbital degrees of freedom, we have found that the electronic structure of certain material systems exhibits the characteristics of unconventional Rashba spin splitting, where the two split Fermi surfaces have the same spin texture. Further investigation into the superconducting state of such systems reveals the following: Based on the spin-fluctuation-induced superconductivity mechanism, this system can generate a superconducting state dominated by spin singlets . This pairing arises from a unique entanglement of spin and orbitals, independent of spin triplets. Moreover, due to the spin-texture characteristics of the Fermi surfaces, this superconducting state itself is a topological superconducting state characterized by a Z2=1 topological invariant. This distinguishes it from existing schemes for realizing topological superconductivity. We predict that such a topological superconducting state may be achievable in some high-temperature superconducting systems with broken centrosymmetry. Using a phenomenological superconducting theory, we find that for unconventional Rashba systems, in addition to the trivial s-wave superconducting state with zero momentum, the system can also produce a finite-momentum pairing superconducting state. The coexistence of these two states can explain certain characteristics of the pairing density wave state in iron-based superconductors. Furthermore, we propose utilizing the proximity effect in superconductivity to realize a finite-momentum pairing LO superconducting state in more general unconventional Rashba systems.

报告人简介：郝 宁，中国科学院合肥物质科学研究院强磁场科学中心研究员，中国科学技术大学博导；2006年本科毕业于山东大学，2011年博士毕业于中科院物理所，此后在美国和香港做研究，2016年加入中科院强磁场科学中心；主要利用凝聚态物理相关的理论以及第一性原理计算方法研究量子材料中的新现象和新效应等，研究体系涵盖高温超导，拓扑材料，磁性材料，低维材料等；曾获中科院百人计划以及国家优秀青年科学基金支持。