The fate of interaction-driven topological insulators under disorder

TL;DR

This paper investigates how disorder impacts interaction-driven topological insulators at quadratic band crossing points, revealing that disorder suppresses topological order and can induce phase transitions to trivial insulators.

Contribution

It provides a comprehensive renormalization group analysis of disorder effects on topological phases in QBCP systems, considering all possible instabilities and phases.

Findings

Disorder suppresses the critical temperature for topological order.

Strong disorder can induce a transition to a trivial insulating phase.

Disorder generally diminishes the stability of topologically non-trivial phases.

Abstract

We analyze the effect of disorder on the weak-coupling instabilities of quadratic band crossing point (QBCP) in two-dimensional Fermi systems, which, in the clean limit, display interaction- driven topological insulating phases. In the framework of a renormalization group procedure, which treats fermionic interactions and disorder on the same footing, we test all possible instabilities and identify the corresponding ordered phases in the presence of disorder for both single-valley and two-valley QBCP systems. We find that disorder generally suppresses the critical temperature at which the interaction-driven topologically non-trivial order sets in. Strong disorder can also cause a topological phase transition into a topologically trivial insulating state.