Instability and topological robustness of Weyl semimetals against Coulomb interaction

TL;DR

This paper investigates how long-range Coulomb interactions affect the stability and topological properties of Weyl semimetals, revealing that their topological features remain robust despite interaction-induced symmetry breaking.

Contribution

It provides a self-consistent mean-field analysis showing the persistence of topological invariants in Weyl semimetals under Coulomb interactions.

Findings

Chiral symmetry breaking occurs at strong interactions.

Interband excitonic pairing significantly influences the band structure.

Topological Chern number jumps are retained despite interactions.

Abstract

There is a close connection between various new phenomena in Weyl semimetals and the existence of linear band crossings in the single particle description. We show, by a full self-consistent mean-field calculation, how this picture is modified in the presence of long-range Coulomb interactions. The chiral symmetry breaking occurs at strong enough interactions and the internode interband excitonic pairing channel is found to be significant, which determines the gap-opened band profile varying with interaction strength. Remarkably, in the resultant interacting phase, finite band Chern number jumps in the three-dimensional momentum space are retained, indicating the robustness of the topologically nontrivial features.