The Berry curvature dipole in Weyl semimetal materials: an ab initio study

TL;DR

This study uses ab initio calculations to analyze the Berry curvature dipole in Weyl semimetals, revealing significant nonlinear Hall effects that could be experimentally observed, especially in type-II Weyl semimetals.

Contribution

The paper introduces an ab initio implementation of the Berry curvature dipole formalism to investigate nonlinear responses in Weyl semimetals.

Findings

Type-II Weyl semimetals exhibit larger Berry curvature dipoles than type-I.

Nonlinear susceptibilities suggest a detectable nonlinear Hall effect.

Strong tilt in type-II Weyl points enhances nonlinear responses.

Abstract

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 MoTe$_2$-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.