Journal Article

Spatially dispersive circular photogalvanic effect in a Weyl semimetal

Yu, Peng, Liu, Gerui, Kane, Charles L, Mele, Eugene J, Gao, Heng, Liu, Wenjing, Agarwal, Ritesh, Addison, Zachariah, Ji, Zhurun, Rappe, Andrew M, Liu, Zheng

2019

Overview

Weyl semimetals (WSMs) are gapless topological states of matter with broken inversion and/or time reversal symmetry. WSMs can support a circulating photocurrent when illuminated by circularly polarized light at normal incidence. Here, we report a spatially dispersive circular photogalvanic effect (s-CPGE) in a WSM that occurs with a spatially varying beam profile. Our analysis shows that the s-CPGE is controlled by a symmetry selection rule combined with asymmetric carrier excitation and relaxation dynamics. By evaluating the s-CPGE for a minimal model of a WSM, a frequency-dependent scaling behaviour of the photocurrent is obtained. Wavelength-dependent measurements from the visible to mid-infrared range show evidence of Berry curvature singularities and band inversion in the s-CPGE response. We present the s-CPGE as a promising spectroscopic probe for topological band properties, with the potential for controlling photoresponse by patterning optical fields on topological materials to store, manipulate and transmit information.

• Publisher: Nature Publishing Group
• Subject: Circular polarization / Curvature / Electrodes / Experiments / Lasers / Materials science / Metalloids / Optical properties / Phase transitions / Photoelectric effect / Photoelectric emission / Polarized light / Singularities / Symmetry / Topology