Resonant transport in Kekulé-distorted graphene nanoribbons

Abstract

The formation of a superlattice in graphene can serve as a way to modify its electronic band structure and thus to engineer its electronic transport properties. Recent experiments have discovered a Kekulé bond ordering in graphene deposited on top of a copper substrate, leading to the breaking of the valley degeneracy while preserving the highly desirable feature of linearity and gapless character of its band dispersion. In this paper, we study the effects of a Kekulé distortion in zigzag graphene nanoribbons in both the subband spectrum and on its electronic transport properties. We extend our study to also investigate the electronic conductance in graphene nanoribbons composed of sequentially ordered ν = ± 1 Kek-Y superlattices. We find interesting resonances in the conductance response emerging in the otherwise energy gap regions, which scales with the number of Kek-Y interfaces minus one. Such features resemble the physics of resonant tunneling behavior observed in semiconductor heterostructures. Our findings provide a possible way to measure the strength of the Kekulé parameter in graphene nanoribbons.