paper

Anderson's theorem for correlated insulating states in twisted bilayer graphene

arXiv:2207.11281 · doi:10.1103/PhysRevLett.130.076204

Abstract

The emergence of correlated insulating phases in magic-angle twisted bilayer graphene exhibits strong sample dependence. Here, we derive an Anderson theorem governing the robustness against disorder of the Kramers intervalley coherent (K-IVC) state, a prime candidate for describing the correlated insulators at even fillings of the moiré flat bands. We find that the K-IVC gap is robust against local perturbations, which are odd under , where and denote particle-hole conjugation and time reversal, respectively. In contrast, -even perturbations will in general induce subgap states and reduce or even eliminate the gap. We use this result to classify the stability of the K-IVC state against various experimentally relevant perturbations. The existence of an Anderson theorem singles out the K-IVC state from other possible insulating ground states.

arXiv comment5 pages

References in corpus (42)

Cited by in corpus (6)