Graphene superlattice with periodically modulated Dirac gap

TL;DR

This paper theoretically investigates a graphene superlattice with periodic gap modulation, revealing the emergence of new Dirac points and interface states that significantly alter the electronic spectrum.

Contribution

It introduces a model for a graphene superlattice with periodic gap modulation and derives conditions for the appearance of new Dirac points and interface states.

Findings

New Dirac points appear under specific conditions.

The gap between minibands can close due to these Dirac points.

Interface states form at certain system parameters.

Abstract

Graphene-based superlattice (SL) formed by a periodic gap modulation is studied theoretically using a Dirac-type Hamiltonian. Analyzing the dispersion relation we have found that new Dirac points arise in the electronic spectrum under certain conditions. As a result, the gap between conduction and valence minibands disappears. The expressions for the position of these Dirac points in ${\bf k}$-space and threshold value of the potential for their emergence were obtained. At some parameters of the system, we have revealed interface states which form the top of the valence miniband.