Anomalous Spatial Shift in Interface Reflection and Its Quantized Circulation

报告题目：Anomalous Spatial Shift in Interface Reflection and Its Quantized Circulation

报告时间：9.3日下午2点

报告地点：腾讯会议ID 502 716 928

报告人：杨声远副教授（新加坡科技设计大学）

主持人: 董 帅

Abstract: In geometric optics, it is known that a light beam can undergo a peculiar spatial shift when reflected at an optical interface. The longitudinal and the transverse components of this shift are respectively known as the Goos-Hanchen and the Imbert-Fedorov effects. In recent years, analogous effects have been studied in context of electronic systems, which exhibit distinct features. In this talk, I will introduce our recent works, which discovered the shift in the process of Andreev reflection. Here, the shift occurs when an incident electron beam is reflected as a hole beam at a metal/superconductor junction interface. Interestingly, for unconventional superconductors, a sizable shift can exist and show characteristic behaviors for each pairing type. We further reveal a quantized physical quantity in this effect, i.e., the circulation of the shift in the interface momentum space. We show that the circulation can capture the topological charges in the band structures, such as Chern numbers for the Weyl or multi-Weyl points. The predicted effect is fundamental and ubiquitous, and it offers a promising tool to characterize topological materials and unconventional superconductors.

杨声远，江苏省南京人。2001-2002年: 清华大学电气自动化专业。2002-2005: 香港大学，数学物理专业，获理学学士。2005-2011年：得克萨斯大学奥斯汀分校，凝聚态物理，获博士学位。2011-2013年：休斯敦CGG Veritas US Services公司工作，地质分析成像工程师。2013年起在新加坡科技设计大学担任助理教授，副教授。以往的研究课题包括磁性材料的磁动力学，二次谐波的发射理论，反常霍尔效应，二维材料/拓扑材料的物理性质。目前的研究方向包括拓扑半金属，拓扑绝缘体，二维材料和纳米结构的物理性质，电子晶体，自旋和谷电子学，量子输运等。