Center for Correlated Electron Systems

Seminar

Linear and nonlinear optical responses of topological semimetals

March 8, 2019l Hit 298
Date : July 26, 2018 16:00 ~ 17:30
Speaker : Dr. Seongjin Ahn(Seoul National University)
Location : Bldg. 19, Rm. 210
Topological semimetals have emerged as a new frontier in condensed matter study due to their unique band structures characterized by linear band touching at zero dimensional points or one-dimensional lines.  In this talk, we investigate their linear and non-linear optical responses. First, we introduce our recent works on the optical conductivity of multi-Weyl and nodal line semimetals. For multi-Weyl semimetals, we show that the frequency dependence of optical conductivities obeys scaling relations that are derived from the winding number. For nodal line semimetals, we show that the low-frequency conductivity has a rich spectral structure which can be understood using scaling rules derived from the geometry of the Fermi surface. For both the materials, we discuss possible experimental implications of our results, suggesting that they can serve as a guidance for optical experiments. Second, we review the recent progress of nonlinear optical responses of Weyl semimetals, focusing on their topological aspect and potential use as a nonlinear optical device. Then we discuss its possible extension to other emerging topological semimetals and finalize the talk with some future perspectives.