Influence of the surface states on the nonlinear Hall effect in Weyl semimetals

TL;DR

This study reveals that surface states significantly influence the nonlinear Hall effect in Weyl semimetals, especially in the type-II phase, with implications for material design and interfacial engineering.

Contribution

It demonstrates how surface states affect the nonlinear Hall response in Weyl semimetals, highlighting the importance of slab geometry and surface contributions in these materials.

Findings

Surface states contribute substantially to the Berry curvature dipole in type-II Weyl semimetals.

The nonlinear Hall response shows strong thickness dependence due to surface states.

First-principles calculations confirm the impact of surface states in realistic materials like WTe₂.

Abstract

We investigate the influence of surface states on the nonlinear Hall response of non-centrosymmetric time-reversal invariant Weyl semimetals. To do so, we perform a tomography of the Berry curvature dipole in a slab system using a minimal two-band model. We find that in the type-I phase, the nonlinear Hall response is not particularly sensitive to the presence of Fermi arcs or other trivial surface states. However, in the type-II phase, we find that these surface states contribute substantially to the Berry curvature dipole, leading to a strong thickness dependence of the nonlinear Hall response. This feature depends on the nature of the surface states and, henceforth, on the slab geometry adopted. In order to assess the validity of this scenario for realistic systems, we performed Berry curvature dipole calculations by first principles on the WTe$_2$, confirming the dramatic impact of surface states for selected slab geometries. Our results suggest that surface states, being topological or not, can contribute much more efficiently to the nonlinear Hall response than bulk states. This prediction is not limited to topological semimetals and should apply to topologically trivial non-centrosymmetric materials and heterostructures, paving the way to interfacial engineering of the nonlinear Hall effect.