Atomic line defects and topological superconductivity in unconventional superconductors

2020-04-20 (周一) 10:00

报告摘要:In this talk, I will first introduce my research experience in the strongly correlated systems. Then I will focus on our recent work on realizing topological superconductors (TSCs) via the line defect in the unconventional superconductors. Here, we propose a novel route toward emergent quasi-one-dimensional (1D) TSCs in naturally embedded quantum structures such as atomic line defects in unconventional spin-singlet s-wave and d-wave superconductors. We show that inversion symmetry breaking and charge transfer due to the missing atoms lead to the occupation of incipient impurity bands and mixed parity spin singlet and triplet Cooper pairing of neighboring electrons traversing the line defect. Nontrivial topological invariants arise and occupy a large part of the parameter space, including the time reversal symmetry breaking Zeeman coupling due to applied magnetic field or defect-induced magnetism, creating TSCs in different topological classes with robust Majorana zero modes at both ends of the line defect. Beyond providing a novel mechanism for the recent discovery of zero-energy bound states at both ends of an atomic line defect in monolayer Fe(Te,Se) superconductors, the findings pave the way for new material realizations of the simplest and most robust 1D TSCs using embedded quantum structures in unconventional superconductors with large pairing energy gaps and high transition temperatures.

报告人简介:张燚博士2008年毕业于中国科学技术大学物理系,之后赴美国波士顿学院读博士,师从Kevin Bedell教授,博士期间主要研究朗道费米液体理论。在2014年获得物理学博士学位后,他前往路易斯安纳州立大学Mark Jarrell教授组做博士后,主要的工作集中在发展和拓展DMFT相关的数值计算方法来处理存在无序和相互作用的强关联体系。他在2019年加入卡弗里理论科学研究所跟张富春教授做博士后,这段时间他的研究方向转移到了魔角双层石墨烯以及在非常规超导体中寻找马约拉纳零能模的方向。