Excitonic gap, phase transition, and quantum Hall effect in graphene: strong-coupling regime

TL;DR

This paper models the phase transition in graphene under strong magnetic fields, explaining the observed quantum Hall plateaus through excitonic and spin gaps in a strong-coupling regime.

Contribution

It introduces a phenomenological model capturing excitonic and spin gaps to explain the quantum Hall effect in graphene under strong magnetic fields.

Findings

Reproduces experimental Hall conductivity with additional plateaus.

Describes phase transition linked to excitonic and spin gap formation.

Discusses behavior without enhanced Zeeman splitting.

Abstract

We suggest that physics underlying the recently observed removal of sublattice and spin degeneracies in graphene in a strong magnetic field describes a phase transition connected with the generation of excitonic and spin gaps. The strong-coupling regime is described using a phenomenological model with enhanced Zeeman splitting (spin gap) and excitonic gaps. The experimental form of the Hall conductivity $\sigma_{xy}$ with the additional $\nu= 0, \pm 1$ plateaus is reproduced. The form of $\sigma_{xy}$ in the case of a strong-coupling regime with no enhanced Zeeman splitting is also discussed.