报告时间：2021-11-17 14:00 腾讯会议ID 528 884 858

报告题目：First-principles investigation of quantum materials under light irradiation

报告人：Jia-Tao Sun，Beijing Institute of Technology, Beijing, 100081, China

报告摘要:Recent advances in ultrafast spectroscopy open a route toward engineering new phase of solids with optical pumping. The nonequilibrium electronic states of solids periodically driven by the electromagnetic field manifest a novel way of engineering topological states which don't exist at equilibrium conditions. Firstly, using first-principles calculations and Floquet theorem, we studied the dressed states of black phosphorous and graphene under periodic driving by incident light. Secondly, the lattice dynamics of type-II Weyl semimetal WTe2 under linearly polarized light was studied. It is found that the WTe2 exhibiting unexpected orbital-selective photoexcitation have been induced striking transition among several topologically-distinct phases mediated by effective electron-phonon coupling. The switchable interlayer shear motion depending on the incident light polarization lead to not only the annihilation of Weyl quasiparticle pairs, but the controllable separation of Weyl points. Our works show new prospective on manipulating the topologically-distinct phase by using coherent control of electrons and lattices dynamics simultaneously.

References

[1]Liu H., Sun J.-T., Cheng C., Liu F., and Meng S. Photoinduced Nonequilibrium Topological States in Strained Black Phosphorus [J]. Phys. Rev. Lett. 2018, 120: 237403.

[2]Guan M. X., Wang E., You P. W., Sun J. T., Meng S. Manipulating Weyl quasiparticles by orbital-selective photoexcitation in WTe2. Nature Communications, 2021, 12: 1885.

报告人简介:孙家涛，2008年中科院物理所凝聚态物理学博士毕业。2009-2013年先后在新加坡国立大学和美国犹他大学从事博士后研究员工作。2014年加入中科院物理所任副研究员、博导。2019年加入北京理工大学，现为集成电路与电子学院教授、博导。研究领域是利用第一性原理计算方法研究量子材料的新奇效应，已发表学术文章70余篇，被引用2000余次。近年来主要关注光场诱导量子体系的非平衡物态及其拓扑相变。