报告题目:Topological Photo Electric Effect in Topological Phase Transition
摘要:
Band inversion is crucial to generate nontrivial band topology. It is an intuitive and convenient picture for searching topological materials. The identification of band inversion from both experimental and theoretical methods is the first and crucial step. The component of the wavefunction is generally used to label a band, such as the local orbitals and the irreducible representations. The band structure calculations can easily obtain the wavefuctions and based on this, the symmetry indicator theory and/or topological quantum chemistry has been proposed and widely used to judge the possible band inversion through the symmetry information at high symmetry k-points. On the other hand, the direct detection of these information experimentally is challenge. It is well known that the optical response of solids is one of the physical processes intrinsically related with two or more bands. The energy gap and the related symmetries of these bands determine the optical properties both in linear and nonlinear responses. In this talk, I will discuss one of the nonlinear optical effects, shift current, in non-centrosymmetric system to study its dependence on the topological phase transition driven by band inversion. Two cases have been studied, one is in the weak light-field and the shift current can be calculated within perturbation. The other one is under strong light-field and the role of shift current in generating high-harmonic generation is treated using time-dependent density matrix method. We argue that the band inversion can cause some effects in the optical response and the detection of them can be used to identify the topological phase transition with careful analysis.
个人简介:
翁红明,中科院物理所 研究员,博士生导师,2017年9月起任理论室副主任。研究拓扑量子态及其材料计算研究,磁光效应,非线性光学效应等第一性原理计算。主要从事计算凝聚态物理方向的研究工作,一方面致力于计算方法和程序的开发,另一方面着重于凝聚态物质中新奇量子现象的计算研究。迄今(2022年2月)共发表SCI论文200余篇,被引用21000余次,h-因子57。2018-2021连续四年入选科睿唯安“全球高被引科学家”。
中科院物理研究所