Local Hall Conductivity in Disordered Topological Insulators

TL;DR

This paper derives a local Hall conductivity expression for disordered topological insulators, revealing how disorder influences topological phases and suggesting experimental methods for visualization.

Contribution

It introduces a new expression for local Hall conductivity in disordered systems and explores how disorder affects topological phase stability and the topological Anderson insulator.

Findings

Disorder can expand the Chern insulating regime.

Breaking a disordered patch into smaller patches can enhance the topological Anderson insulator.

Results motivate local measurement techniques for visualizing Hall currents.

Abstract

We derive the expression for the local Hall conductivity for systems that lack translation symmetry and use it to study the local fluctuations of the Hall signal around disordered patches in magnetic insulators. We find that the regime in parameter space over which the system is a Chern insulating state increases upon inclusion of non-magnetic potential disorder. In addition, the phase space over which the topological Anderson insulator exists can be enhanced by breaking up a single disordered patch into multiple smaller patches with the same total amount of disorder. We expect our results will motivate the next generation of local scanning and local impedance spectroscopy experiments to visualize Hall currents around patches in the bulk of a disordered topological insulator.