Transition from metal to higher-order topological insulator driven by random flux

TL;DR

This paper demonstrates that random flux can induce a full metal-insulator transition in a 2D topological model, leading to an extrinsic higher-order topological insulator with zero-energy corner modes, challenging previous beliefs.

Contribution

It reveals that random flux can drive a metal-insulator transition and produce higher-order topological insulators, providing a new mechanism for topological phase transitions in disordered systems.

Findings

Random flux induces a full metal-insulator transition in the 2D Su-Schrieffer-Heeger model.

The resulting insulator can be an extrinsic higher-order topological insulator with zero-energy corner modes.

Critical exponent of the transition is approximately 2.48.

Abstract

Random flux is commonly believed to be incapable of driving full metal-insulator transitions in non-interacting systems. Here we show that random flux can after all induce a full metal-band insulator transition in the two-dimensional Su-Schrieffer-Heeger model. Remarkably, we find that the resulting insulator can be an extrinsic higher-order topological insulator with zero-energy corner modes in proper regimes, rather than a conventional Anderson insulator. Employing both level statistics and finite-size scaling analysis, we characterize the metal-band insulator transition and numerically extract its critical exponent as $\nu=2.48\pm0.08$. To reveal the physical mechanism underlying the transition, we present an effective band structure picture based on the random flux averaged Green's function.