Weyl Semimetal in the Strong Coulomb Interaction Limit

TL;DR

This paper investigates the impact of strong long-range Coulomb interactions on Weyl semimetals, revealing spontaneous parity symmetry breaking and the emergence of a new type of Weyl semimetal with broken time-reversal and parity symmetries.

Contribution

It introduces a theoretical analysis of Weyl semimetals under strong Coulomb interactions using lattice gauge theory and mean-field approximation, highlighting a novel symmetry-breaking phase.

Findings

Parity symmetry is spontaneously broken in the strong coupling limit.

A new Weyl semimetal phase with broken time-reversal and parity symmetries appears.

A possible global phase diagram for correlated Weyl semimetals is proposed.

Abstract

We study the effects of strong $1/r$ long-range Coulomb interactions in a Weyl semimetal. We consider a three-dimensional (3D) Dirac fermion system on a lattice with a time-reversal symmetry breaking term, and take into account $1/r$ long-range Coulomb interactions between the bulk electrons. This model is regarded as the case where magnetic impurities are doped into the bulk of a 3D topological insulator. With the use of the strong coupling expansion of the lattice gauge theory and the mean-field approximation, we analyze the system from the strong coupling limit. It is shown that parity symmetry of the system is spontaneously broken in the strong coupling limit, and a different type of the Weyl semimetal, in which time-reversal and parity symmetries are broken, appears in the strong coupling limit. A possible global phase diagram of a correlated Weyl semimetal is presented.