Ballistic guided electrons against disorder in graphene nanoribbons

TL;DR

This paper investigates internal waveguiding mechanisms in graphene nanoribbons, such as strain folds and scalar potentials, to enhance ballistic conductance and robustness against edge disorder, with potential applications in nanotechnology.

Contribution

It numerically evaluates the effectiveness of strain folds and scalar potentials as internal waveguides in GNRs against disorder, demonstrating improved conductance and robustness.

Findings

Internal waveguides improve conductance in GNRs

Presence of quasi-ballistic conductance plateaus

Enhanced robustness against edge disorder

Abstract

Graphene nanoribbons (GNRs) are natural waveguides for electrons in graphene. Nevertheless, unlike micron-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 (LDOS) of zigzag GNRs and characterize the performance of these different physical waveguiding effects in both types of disorder. 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 up to be applied in modern nanotechnology and being experimentally tested.