Nematic insulator at charge neutrality in twisted bilayer graphene

Abstract

We investigate twisted bilayer graphene near charge neutrality using a generalized Bistritzer-MacDonald continuum model, accounting for corrugation effects. The Fermi velocity vanishes for particular twist angles properly reproducing the physics of the celebrated magic angles. Using group representation theory, we identify all contact interaction potentials compatible with the symmetries of the model. This enables us to identify two classes of quartic interactions leading to either the opening of a gap or to nematic ordering. We then implement a renormalization group analysis to study the competition between these interactions for a twist angle approaching the first magic value. This combined group theory-renormalization study reveals that the proximity to the first magic angle favors the occurrence of a layer-polarized, gapped state with a spatial modulation of interlayer correlations, which we call nematic insulator.

6.5 + 11 pages, 7 + 2 figures, 2 + 3 tables

References in corpus (4)

• The crucial role of atomic corrugation on the flat bands and energy gaps of twisted bilayer graphene at the "magic angle" $\theta \sim 1.08^{\circ }$
• General continuum model for twisted bilayer graphene and arbitrary smooth deformations
• Valley magnetism, nematicity, and density wave orders in twisted bilayer graphene
• Identification of superconducting pairing symmetry in twisted bilayer graphene using in-plane magnetic field and strain

Cited by in corpus (6)

• Dynamical correlations and order in magic-angle twisted bilayer graphene
• Quantum Monte Carlo sign bounds, topological Mott insulator and thermodynamic transitions in twisted bilayer graphene model
• Finite-temperature critical behaviors in 2D long-range quantum Heisenberg model
• Valley-polarized nematic order in twisted moiré systems: In-plane orbital magnetism and non-Fermi liquid to Fermi liquid crossover
• Twisted bilayer graphene at charge neutrality: competing orders of SU(4) Dirac fermions
• Strain-tuned quantum criticality in electronic Potts-nematic systems