Topological Insulator in the Presence of Spatially Correlated Disorder

TL;DR

This paper explores how spatially correlated disorder affects two-dimensional topological insulators, revealing that such correlations can suppress the topological Anderson insulator phase and are linked to a quantum percolation transition.

Contribution

It extends previous studies by analyzing the impact of correlated disorder on topological phases and generalizes an effective medium theory to include these correlations.

Findings

Correlated disorder can suppress the topological Anderson insulator phase.

The suppression is linked to a quantum percolation transition.

The generalized theory aligns well with numerical simulations.

Abstract

We investigate the effect of spatially correlated disorder on two-dimensional topological insulators and on the quantum spin Hall effect which the helical edge states in these systems give rise to. Our work expands the scope of previous investigations which found that uncorrelated disorder can induce a nontrivial phase called the topological Anderson insulator (TAI). In extension of these studies, we find that spatial correlations in the disorder can entirely suppress the emergence of the TAI phase. We show that this phenomenon is associated with a quantum percolation transition and quantify it by generalizing an existing effective medium theory to the case of correlated disorder potentials. The predictions of this theory are in good agreement with our numerics and may be crucial for future experiments.