A Lorentz-violating low-energy model for the bilayer Graphene

TL;DR

This paper introduces a Lorentz-violating model for low-energy electrons in AA-bilayer graphene, revealing effects like photon mass generation and anomalous thermal currents due to Lorentz symmetry breaking.

Contribution

It presents a novel Lorentz-violating theoretical framework for AA-bilayer graphene's low-energy excitations, linking symmetry violation to observable electromagnetic and thermal phenomena.

Findings

Photon acquires mass in the model

Lorentz violation induces anomalous thermal currents

Model describes fermionic quasiparticles with Lorentz-violating parameters

Abstract

In this work, we propose a model with Lorentz symmetry violation which describes the electronic low energy limit of the AA-bilayer graphene (BLG) system. The AA-type bilayer is known to preserve the linear dispersion relation of the graphene layer in the low energy limit. The theoretical model shows that in the BLG system, a time-like vector can be associated with the layer separation and contributes to the energy eigenstates. Based on these properties, we can describe in a $(2+1)$-dimensional space-time the fermionic quasi-particles that emerge in the low-energy limit with the introduction of a Lorentz-violating parameter, in analogy with the $(3 + 1)$-dimensional Standard Model Extension (SME). Moreover, we study the consequences of the coupling of these fermionic quasi-particles with the electromagnetic field, and we show via effective action that the low-energy photon acquires a massive spectrum. Finally, using the hydrodynamic approach in the collisionless limit, one finds that the LSV generates a new kind of anomalous thermal current to the vortexes of the system via coupling of the LSV vector.