Spatially dispersive circular photogalvanic effect in a Weyl semimetal

• Main Authors: Ji, Zhurun, Liu, Gerui, Addison, Zachariah, Liu, Wenjing, Yu, Peng, Gao, Heng, Liu, Zheng, Rappe, Andrew M., Kane, Charles L., Mele, Eugene J., Agarwal, Ritesh
• Other Authors: School of Materials Science and Engineering
• Format: Article
• Language: English
• Published: 2020
• Subjects: Science::Physics; Nonlinear Optics; Topological Matter
• Online Access: https://hdl.handle.net/10356/143310
• Institution: Nanyang Technological University

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.