Strong Coupling Expansion in a Correlated Three-Dimensional Topological Insulator

TL;DR

This paper investigates how strong Coulomb interactions affect a three-dimensional topological insulator modeled by Wilson fermions, revealing that the topological phase persists even under strong coupling conditions.

Contribution

It introduces a strong coupling expansion approach to analyze electron correlations in 3D topological insulators with Wilson fermions, showing phase stability.

Findings

Coulomb interaction renormalizes the Wilson fermions' bare mass.

Topological insulator phase remains stable in the strong coupling limit.

Strong coupling effects do not destroy the topological phase.

Abstract

Motivated by recent studies which show that topological phases may emerge in strongly correlated electron systems, we theoretically study the strong electron correlation effect in a three-dimensional topological insulator, which effective Hamiltonian can be described by the Wilson fermions. We adopt 1/r long-range Coulomb interaction as the interaction between the bulk electrons. Based on the U(1) lattice gauge theory, the strong coupling expansion is applied by assuming that the effective interaction is strong. It is shown that the effect of the Coulomb interaction is equivalent to the renormalization of the bare mass of the Wilson fermions, and that as a result, the topological insulator phase survives in the strong coupling limit.