Tunable Band Gap in Graphene with a Non-Centrosymmetric Superlattice Potential

TL;DR

This paper demonstrates that applying a non-centrosymmetric superlattice potential to graphene can induce and control a band gap at the Dirac point, with potential tunability via external parameters.

Contribution

It introduces a method to open and tune a band gap in graphene using a non-centrosymmetric superlattice potential, supported by numerical calculations.

Findings

A band gap appears at the Dirac point when inversion symmetry is broken.

The band gap can be controlled by external potential and lattice constant.

A second-generation Dirac point also exhibits a band gap.

Abstract

We show that, if graphene is subjected to the potential from an external superlattice, a band gap develops at the Dirac point provided the superlattice potential has broken inversion symmetry. As a numerical example, we calculate the band structure of graphene in the presence of an external potential due to periodically patterned gates arranged in a triangular graphene superlattice (TGS) with broken inversion symmetry, and find that a band gap is created at both the original and "second generation" Dirac point. The gap can be controlled, in principle, by changing the external potential and the lattice constant of the TGS.