Density wave instabilities and surface state evolution in interacting Weyl semimetals

TL;DR

This paper explores how interactions in Weyl semimetals influence their electronic surface states and can induce various density wave instabilities, potentially leading to novel quantum anomalous Hall states.

Contribution

It provides a detailed analysis of the effects of Hubbard interactions on Weyl semimetals, revealing conditions for surface state persistence and bulk gap opening.

Findings

Identification of spin and charge density wave instabilities

Scenarios where Weyl nodes are gapped but Fermi arcs remain

Realization of quantum anomalous Hall states

Abstract

We investigate the interplay of many-body and band structure effects of interacting Weyl semimetals (WSM). Attractive and repulsive Hubbard interactions are studied within a model for a time-reversal-breaking WSM with tetragonal symmetry, where we can approach the limit of weakly coupled planes and coupled chains by varying the hopping amplitudes. Using a slab geometry, we employ the variational cluster approach to describe the evolution of WSM Fermi arc surface states as a function of interaction strength. We find spin and charge density wave instabilities which can gap out Weyl nodes. We identify scenarios where the bulk Weyl nodes are gapped while the Fermi arcs still persist, hence realizing a quantum anomalous Hall state.