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

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 $\mathcal{P}\mathcal{T}$, where $\mathcal{P}$ and $\mathcal{T}$ denote particle-hole conjugation and time reversal, respectively. In contrast, $\mathcal{P}\mathcal{T}$-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.

5 pages

References in corpus (10)

• Fractional Chern insulators in magic-angle twisted bilayer graphene
• Imaging Chern mosaic and Berry-curvature magnetism in magic-angle graphene
• Global Phase Diagram of the Normal State of Twisted Bilayer Graphene
• Moiré Commensurability and the Quantum Anomalous Hall Effect in Twisted Bilayer Graphene on Hexagonal Boron Nitride
• Theory of correlated insulators and superconductivity in twisted bilayer graphene
• General continuum model for twisted bilayer graphene and arbitrary smooth deformations
• Spectroscopy of Twisted Bilayer Graphene Correlated Insulators
• Impurity-induced triple point fermions in twisted bilayer graphene
• Detecting symmetry breaking in magic angle graphene using scanning tunneling microscopy
• Domain Formation Driven by the Entropy of Topological Edge Modes

Cited by in corpus (6)

• Anomalous Coherence Length in Superconductors with Quantum Metric
• Inducing superconductivity in bilayer graphene by alleviation of the Stoner blockade
• Double-dome Unconventional Superconductivity in Twisted Trilayer Graphene
• Disorder scattering in classical flat channel transport of particles between twisted magnetic square patterns
• Coulomb-driven band unflattening suppresses $K$-phonon pairing in moiré graphene
• Constraints from anti-unitary symmetries on phase diagrams of sign problem-free models