Landau levels in deformed bilayer graphene at low magnetic fields

TL;DR

This paper reviews how uniaxial strain influences the electronic properties and Landau levels of bilayer graphene, revealing three distinct regimes and predicting changes in quantum Hall filling factors under strain.

Contribution

It introduces a strain-induced term in the low-energy Hamiltonian and characterizes three regimes of electronic dispersion in strained bilayer graphene.

Findings

Strain modifies the low-energy band structure of bilayer graphene.

Weak magnetic fields with sufficient strain favor filling factor ±4 over ±8.

Activation gaps at filling factor ±4 are weakly dependent on magnetic field in one regime.

Abstract

We review the effect of uniaxial strain on the low-energy electronic dispersion and Landau level structure of bilayer graphene. Based on the tight-binding approach, we derive a strain-induced term in the low-energy Hamiltonian and show how strain affects the low-energy electronic band structure. Depending on the magnitude and direction of applied strain, we identify three regimes of qualitatively different electronic dispersions. We also show that in a weak magnetic field, sufficient strain results in the filling factor ff=+-4 being the most stable in the quantum Hall effect measurement, instead of ff=+-8 in unperturbed bilayer at a weak magnetic field. To mention, in one of the strain regimes, the activation gap at ff=+-4 is, down to very low fields, weakly dependent on the strength of the magnetic field.