Higher-order Topological Anderson Insulators

TL;DR

This paper demonstrates how disorder can induce a higher-order topological insulator phase with quadrupole moments in a 2D system, revealing new topological phenomena and localization behaviors.

Contribution

It introduces the concept of higher-order topological Anderson insulators, showing disorder-induced topological phases and their properties in a 2D system with chiral symmetry.

Findings

Disorder induces a quadrupole topological phase from a trivial phase.

Identification of gapped, gapless, and Griffiths regimes with distinct localization properties.

Proposal of an experimental scheme using topoelectrical circuits to observe these phenomena.

Abstract

We study disorder effects in a two-dimensional system with chiral symmetry and find that disorder can induce a quadrupole topological insulating phase (a higher-order topological phase with quadrupole moments) from a topologically trivial phase. Their topological properties manifest in a topological invariant defined based on effective boundary Hamiltonians, the quadrupole moment, and zero-energy corner modes. We find gapped and gapless topological phases and a Griffiths regime. In the gapless topological phase, all the states are localized, while in the Griffiths regime, the states at zero energy become multifractal. We further apply the self-consistent Born approximation to show that the induced topological phase arises from disorder renormalized masses. We finally introduce a practical experimental scheme with topoelectrical circuits where the predicted topological phenomena can be observed by impedance measurements. Our work opens the door to studying higher-order topological Anderson insulators and their localization properties.