Gap generation and phase diagram in strained graphene in a magnetic field

TL;DR

This paper investigates how strain-induced pseudomagnetic fields and real magnetic fields influence the electronic phases of graphene, revealing a phase diagram with various quantum Hall states in a low-energy effective model.

Contribution

It provides a detailed analysis of the phase diagram of strained graphene under magnetic fields, highlighting the impact of interaction couplings on quantum Hall states.

Findings

Identification of ferromagnetic, antiferromagnetic, and canted antiferromagnetic phases.

Sensitivity of the phase diagram to four-fermion interaction couplings.

Dependence of quantum Hall states on strain and magnetic field signs.

Abstract

The gap equation for Dirac quasiparticles in monolayer graphene in constant magnetic and pseudomagnetic fields, where the latter is due to strain, is studied in a low-energy effective model with contact interactions. Analyzing solutions of the gap equation, the phase diagram of the system in the plane of pseudomagnetic and parallel magnetic fields is obtained in the approximation of the lowest Landau level. The three quantum Hall states, ferromagnetic, antiferromagnetic, and canted antiferromagnetic, are realized in different regions of the phase diagram. It is found that the structure of the phase diagram is sensitive to signs and values of certain four-fermion interaction couplings which break the approximate spin-value SU(4) symmetry of the model.