paper

Ordered states in AB bilayer graphene in SU(4)-symmetric model

arXiv:2411.01309 · doi:10.1103/PhysRevB.111.205421

Abstract

We apply SU(4)-symmetric model to examine possible ordered states in AB stacked bilayer graphene (AB-BLG). The Hamiltonian of the system possesses this symmetry under certain assumptions. In such a model the multicomponent order parameter can be presented as a matrix . Using a mean field approximation, we derive a self-consistency equation for . Among possible solutions of the obtained equation there are anomalous quantum Hall states, spin, charge, spin-valley density waves, inter-layer excitonic phases and their combinations. We argue that the proposed approach is a useful tool for classification of the ordered states in AB-BLG. The ordered states of the SU(4)-symmetric model demonstrate extensive degeneracies. The degeneracies can be removed by taking into account the neglected non-SU(4)-symmetric terms, disorder, substrate, as well as other perturbations. The ordered states have varying sensitivity to these factors. This suggests that, for AB-BLG, a ground state ordering type is a non-universal property, susceptible to particulars of extrinsic conditions.

11 pages, 1 figure, almost identical to published version

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