Quantum Hall States in Graphene from Strain-Induced Nonuniform Magnetic Fields

TL;DR

This paper investigates how strain-induced nonuniform magnetic fields in graphene create unique quantum Hall states, revealing differences from traditional magnetic fields and proposing experimental tests involving sublattice polarization.

Contribution

It introduces a theoretical framework for understanding strain-induced pseudomagnetic fields in graphene and compares predictions with tight-binding calculations, highlighting potential experimental signatures.

Findings

Strain causes nonuniform pseudomagnetic fields in graphene.

Key properties differ from those under real magnetic fields.

Hubbard interactions induce measurable sublattice polarization.

Abstract

We examine strain-induced quantized Landau levels in graphene. Specifically, arc-bend strains are found to cause nonuniform pseudomagnetic fields. Using an effective Dirac model which describes the low-energy physics around the nodal points, we show that several of the key qualitative properties of graphene in a strain-induced pseudomagnetic field are different compared to the case of an externally applied physical magnetic field. We discuss how using different strain strengths allows us to spatially separate the two components of the pseudospinor on the different sublattices of graphene. These results are checked against a tight-binding calculation on the graphene honeycomb lattice, which is found to exhibit all the features described. Furthermore, we find that introducing a Hubbard repulsion on the mean-field level induces a measurable polarization difference between the A and the B sublattices, which provides an independent experimental test of the theory presented here.