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Nonlinear Hall Effect and Photocurrent in Weyl Semimetal Material
Speaker Mr. Yang Zhang, Max Planck Institute for Chemical Physics of Solids
Date 29 November 2017 (Wednesday)
Time 16:00 - 17:30
Venue Lecture Theatre H (Lifts 25-26), Academic Building, HKUST

Noncentrosymmetric metals are anticipated to exhibit a dc photocurrent in the nonlinear optical response caused by the Berry curvature dipole in momentum space. Weyl semimetals (WSMs) are expected to be excellent candidates for observing these nonlinear effects because they carry a large Berry curvature concentrated in small regions, i.e., near the Weyl points. We have implemented the semiclassical Berry curvature dipole formalism into an ab initio scheme and investigated the second-order nonlinear response for two representative groups of materials: the TaAs-family type-I WSMs and MoTe2-family type-II WSMs. Both types of WSMs exhibited a Berry curvature dipole, in which type-II Weyl points are usually superior to the type-I because of the strong tilt. Corresponding nonlinear susceptibilities in several materials promise a nonlinear Hall effect in the dc field limit, which is within the experimentally detectable range. Also photocurrent calculated from second order Kubo formula would be presented in this talk, which is valid in hight frequency optical region.