报告题目: Disorder-induced Quantum Phase Transitions in Second-order Topological Insulators

报告人：汪晨 副教授 （天津大学量子交叉研究中心）

报告时间：2020年9月24日 15:30 - 16:30

报告地点：在线报告（腾讯会议ID：250 726 997, 密码：152152）

报告摘要: 

Given the tremendous interest in finding various three-dimensional second-order topological insulators with exotic in-gap hinge states in the clean limit, and the recent discovery of such topological non-trivial phases in real materials, it is natural to ask whether one can prove their robustness against disorders, which is a defining property of true topological states. In this talk, a comprehensive discussion on the robustness of both strong and weak three-dimensional second-order topological insulators is given. It is numerically shown that both chiral and helical hinge states persist at finite disorders. Self-consistent Born approximation calculations suggest that a quantum phase transition from WSOTI to first-order topological insulators happens when the gap of surface states closes. Electronic transports through such hinge states are studied numerically and analytically. With further increasing disorders, the first-order topological insulator will become a diffusive metal when the gap of bulk gap closes, and finally an Anderson insulator through the Anderson localization. These findings strongly support the generalized bulk-boundary correspondence which claims the topological quantum phase transitions from states in submanifold of (d - n) dimension to that of (d - n + 1) dimension can only happen when the gap of (d - n + 1) dimension manifold closes, irrelevant to the backward scatterings.

参考文献:

[1] C. Wang and X. R. Wang, arXiv: 2005.06740

[2] C. Wang and X. R. Wang, arXiv: 2009.02060