Determine the chirality and spin properties of topological states from ARPES

讲座名称: Determine the chirality and spin properties of topological states from ARPES
讲座时间: 2016-05-06
讲座人: 余睿
形式:
校区: 兴庆校区
实践学分:
讲座内容: 报告题目:Determine the chirality and spin properties of topological states from ARPES 报 告 人:余睿 报告时间:2016年5月6号上午10点 报告地点:中一楼3113室 报告摘要: 角分辨光电子谱实验在测量晶体能带的自旋、轨道、手性等信息中具有重要作用。 报告人将介绍近期在角分辨光电子谱方面开展的两个理论工作。第一个工作将介绍如何通过圆偏振二向色性来探测外尔半金属中外尔点的手性信息。 第二个工作将讨论角分辨光电子谱实验测得的受激电子自旋与材料内部电子的赝自旋、真实自旋的联系。通过研究Bi2Se3和SmB6这两类材料中上述三种自旋,我们发现实验上测得的受激电子自旋指向与光-电子激发矩阵元及材料的晶体对称性密切相关。 上述理论讨论能在自旋分辨和圆偏振二向色性角分辨光电子谱实验中得到证实。 Angle-resolved photoemission spectroscopy (ARPES) experiment is a powerful tool for investigating the spin, orbital, chiral and valleyproperty of electrons in crystalline materials. In this talk, I will introduce two of my recent work. In the first part, we show that the circular dichroism spectra of pumped states near Weyl point is directly related to the chirality of Weyl fermions. We proposed a method to determine the chirality for a given Weylpoint from thecircular dichroism of time-dependent ARPES. In the secondpart, we discuss the connections between pseudo spin, real spin of electrons in materialand spin polarization of photo-emitted electrons out of material. We take two famous topological insulators Bi2Se3and SmB6 as example to show that the spin orientation of photo-electrons forSmB6has different correspondence to pseudo spin and real spin compare to Bi2Se3, due to thedifferent symmetry properties of the photo-emission matrix elements, which can be observed in thespin-resolved andcircular dichroism ARPES experiments.  
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