Local sublattice symmetry breaking for graphene with a centro-symmetric deformation

TL;DR

This paper investigates how a centro-symmetric out-of-plane deformation in graphene causes local sublattice symmetry breaking, revealing strain signatures through LDOS imbalance and characteristic six-fold patterns, supported by analytical and numerical methods.

Contribution

It provides a theoretical analysis of sublattice symmetry breaking in graphene due to localized deformations, with an analytic expression and numerical validation.

Findings

Strain induces LDOS imbalance between sublattices.

Characteristic six-fold symmetry pattern observed.

Analytic scaling law relates deformation parameters to LDOS contrast.

Abstract

We calculate the local density of states (LDOS) for an infinite graphene sheet with a single centro-symmetric out-of-plane deformation, in order to investigate measurable strain signatures on graphene. We focus on the regime of small deformations and show that the strain-induced pseudo- magnetic field induces an imbalance of the LDOS between the two triangular graphene sublattices in the region of the deformation. Real space imaging reveals a characteristic six-fold symmetry pattern where the sublattice symmetry is broken within each fold, consistent with experimental and tight-binding observations. The open geometry we study allows us to make use of the usual continuum model of graphene and to obtain results independent of boundary conditions. We provide an analytic perturbative expression for the contrast between the LDOS of each sub-lattice, showing a scaling law as a function of the amplitude and width of the deformation. We confirm our results by a numerically exact iterative scattering matrix method.