Pseudomagnetic fields and triaxial strain in graphene

TL;DR

This paper investigates how triaxial strain in graphene creates pseudomagnetic fields, leading to pseudo Landau levels and sublattice polarization, with analytical and numerical methods revealing detailed electronic properties.

Contribution

It provides a comprehensive analysis of pseudomagnetic fields in finite graphene regions, especially pseudomagnetic dots, combining analytical Dirac model predictions with numerical tight-binding simulations.

Findings

Pseudomagnetic fields induce pseudo Landau levels in graphene.

The zeroth pseudo Landau level shows sublattice and valley polarization.

Numerical results confirm analytical predictions and explore strain orientation effects.

Abstract

Strain fields in graphene giving rise to pseudomagnetic fields have received much attention due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 Tesla. We examine systems with such strains confined to finite regions ("pseudomagnetic dots") and provide a transparent explanation for the characteristic sublattice polarization occurring in the presence of pseudomagnetic field. In particular, we focus on a triaxial strain leading to a constant field in the central region of the dot. This field causes the formation of pseudo Landau levels, where the zeroth order level shows significant differences compared to the corresponding level in a real magnetic field. Analytic arguments based on the Dirac model are employed to predict the sublattice and valley dependencies of the density of states in these systems. Numerical tight binding calculations of single pseudomagnetic dots in extended graphene sheets confirm these predictions, and are also used to study the effect of the rotating the strain direction and varying the size of the pseudomagnetic dot.