Interaction Protected Topological Insulators with Time Reversal Symmetry

TL;DR

This paper investigates how electron interactions affect the edge states of two-dimensional time reversal topological insulators, revealing that strong interactions can induce a conducting phase even at fillings typically insulating in non-interacting cases.

Contribution

It demonstrates that repulsive interactions can alter the topological protection, leading to a conducting phase at fillings that are insulating in the non-interacting limit, and maps the phase boundaries under disorder.

Findings

Strong interactions induce a conducting phase at even fillings.

Interaction modifies the phase diagram of topological insulators.

Boundaries of conducting phases depend on disorder and filling.

Abstract

Anderson's localization on the edge of two dimensional time reversal (TR) topological insulator (TI) is studied. For the non-interacting case the topological protection acts accordingly to the $\mathbb{Z}_2$ classification, leading to conducting and insulating phases for odd and even fillings respectively. In the presence of repulsive interaction the phase diagram is notably changed. We show that for sufficiently strong values of the interaction the zero temperature fixed point of the TI is conducting, including the case of even fillings. We compute the boundaries of the conducting phase for various fillings and types of disorder.