Third-order topological insulator induced by disorder

TL;DR

This paper reports the discovery of a third-order topological Anderson insulator induced by disorder, characterized by quantized octupole moments and protected corner states, expanding the understanding of disorder-induced topological phases.

Contribution

It introduces the first example of a third-order topological Anderson insulator in three dimensions, with analytical and numerical evidence of its properties and phase transitions.

Findings

Disorder induces a gapped third-order topological phase with protected corner states.

The transition to the topological phase can be accurately modeled with the self-consistent Born approximation.

At higher disorder, the phase transitions from topological insulator to diffusive metal and then to Anderson insulator.

Abstract

We have found the first instance of a third-order topological Anderson insulator (TOTAI). This disorder-induced topological phase is gapped and characterized by a quantized octupole moment and topologically protected corner states, as revealed by a detailed numerically exact analysis. We also find that the disorder-induced transition into the TOTAI phase can be analytically captured with remarkable accuracy using the self-consistent Born approximation. For a larger disorder strength, the TOTAI undergoes a transition to a trivial diffusive metal, that in turn becomes an Anderson insulator at even larger disorder. Our findings show that disorder can induce third-order topological phases in 3D, therefore extending the class of known higher-order topological Anderson insulators.