Elastic Screening of Pseudogauge Fields in Graphene

TL;DR

This study reveals that optical lattice displacements in graphene significantly screen and reshape pseudogauge fields, affecting electronic properties and challenging previous continuum elasticity assumptions.

Contribution

It demonstrates that optical lattice displacements contribute equally to acoustic ones in screening pseudogauge fields, a factor previously overlooked in continuum models.

Findings

Optical displacements reduce pseudomagnetic field magnitude.

Optical effects reshape pseudomagnetic fields in corrugated graphene.

Previous models overestimated strain-induced pseudomagnetic fields.

Abstract

Lattice deformations in graphene couple to the low-energy electronic degrees of freedom as effective scalar and gauge fields. Using molecular dynamics simulations, we show that the optical component of the displacement field, i.e., the relative motion of different sublattices, contributes at equal order as the acoustic component and effectively screens the pseudogauge fields. In particular, we consider twisted bilayer graphene and corrugated monolayer graphene. In both cases, optical lattice displacements significantly reduce the overall magnitude of the pseudomagnetic fields. For corrugated graphene, optical contributions also reshape the pseudomagnetic field and significantly modify the electronic bands near charge neutrality. Previous studies based on continuum elasticity, which ignores this effect, have therefore systematically overestimated the strength of the strain-induced pseudomagnetic field. Our results have important consequences for the interpretation of experiments and design of straintronic applications.