Ballistic guided electrons against disorder in graphene nanoribbons

Abstract

Graphene nanoribbons (GNRs) are natural waveguides for electrons in graphene. Nevertheless, unlike micrometer-sized samples, conductance is nearly suppressed in these narrow graphene stripes, mainly due to scattering with edge disorder generated during synthesis or cut. A possible way to circumvent this effect is to define an internal waveguide that isolates specific modes from the edge disorder and allows ballistic conductance. There are several proposals for defining waveguides in graphene; in this manuscript, we consider strain folds and scalar potentials and numerically evaluate these proposals’ performance against edge and bulk disorder. Using the Green’s function approach, we calculate conductance and the local density of states of zigzag GNRs and characterize the performance of these different physical waveguiding effects in both types of disorders. We found a general improvement in the electronic conductance of GNR due to the presence of the internal waveguiding, with the emergence of plateaus with quasi-ballistic properties and robustness against edge disorder. These findings are ready to be applied in modern nanotechnology and are being experimentally tested.