Topological Anderson Insulator

TL;DR

This paper predicts a new phase called the topological Anderson insulator, where disorder induces topologically protected edge states in a 2D metal, revealing a novel role of impurities in topological phases.

Contribution

It introduces the concept of a topological Anderson insulator, demonstrating how disorder can create topologically protected edge states in two-dimensional systems.

Findings

Disorder can induce a topological phase in 2D metals.

The phase diagram of the topological Anderson insulator is mapped.

Experimental signatures of this phase are outlined.

Abstract

Disorder plays an important role in two dimensions, and is responsible for striking phenomena such as metal insulator transition and the integral and fractional quantum Hall effects. In this paper, we investigate the role of disorder in the context of the recently discovered topological insulator, which possesses a pair of helical edge states with opposing spins moving in opposite directions and exhibits the phenomenon of quantum spin Hall effect. We predict an unexpected and nontrivial quantum phase termed "topological Anderson insulator," which is obtained by introducing impurities in a two-dimensional metal; here disorder not only causes metal insulator transition, as anticipated, but is fundamentally responsible for creating extended edge states. We determine the phase diagram of the topological Anderson insulator and outline its experimental consequences.