Linear and nonlinear optical responses of topological semimetals
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.