Weak quantization of non-interacting topological Anderson insulator

TL;DR

This paper investigates the transition between topological insulators and Anderson insulators under strong disorder, revealing a weak quantization phase characterized by power-law conductance scaling, and analyzes the impact of disorder range on this phase.

Contribution

It introduces the concept of weak quantization topological insulator (WQTI) and links its emergence to the self-energy behavior, supported by analytical and numerical methods.

Findings

Weak quantization exhibits power-law scaling with system size.

Long-range disorder suppresses the topological Anderson insulator phase.

The phase is prevalent in short-range disorder but rare in solid-state systems.

Abstract

We study the transition between the two-dimensional topological insulator (TI) featuring quantized edge conductance and the trivial Anderson insulator (AI) induced by strong disorder. We discover a distinct scaling behavior of TI near the phase transition where the longitudinal conductance approaches the quantized value by a power law with system size, instead of an exponential law in clean TI. This region is thus called the weak quantization topological insulator (WQTI). By using the self-consistent Born approximation, we associate the emergence of the weak quantization with the imaginary part of the effective self-energy acquiring a finite value at strong disorder. We use our analytical theory, supported by direct numerical simulations, to study the effect of disorder range on the topological Anderson insulator. Interestingly, while this phase is quite generic for uncorrelated or short-range disorder, it is strongly suppressed by long-range disorder, perhaps explaining why it has never been seen in solid state systems.