Disorder-induced pseudodiffusive transport in graphene nanoribbons

TL;DR

This paper investigates how binary disorder affects electron transport in graphene nanoribbons, revealing a novel pseudodiffusive regime near the Dirac point caused by impurity-induced evanescent modes.

Contribution

It introduces the concept of intrinsic pseudodiffusive transport in disordered graphene nanoribbons, expanding understanding of phase-coherent transport regimes.

Findings

Evanescent modes dominate transport near the Dirac point at short lengths.

A new pseudodiffusive regime exists without heavily doped contacts.

Effective number of propagating modes and mean free path are significantly modified.

Abstract

We study the transition from ballistic to diffusive and localized transport in graphene nanoribbons in the presence of binary disorder, which can be generated by chemical adsorbates or substitutional doping. We show that the interplay between the induced average doping (arising from the non-zero average of the disorder) and impurity scattering modifies the traditional picture of phase-coherent transport. Close to the Dirac point, intrinsic evanescent modes produced by the impurities dominate transport at short lengths, giving rise to a new regime analogous to pseudodiffusive transport in clean graphene, but without the requirement of heavily doped contacts. This intrinsic pseudodiffusive regime precedes the traditional ballistic, diffusive and localized regimes. The last two regimes exhibit a strongly modified effective number of propagating modes, and a mean free path which becomes anomalously large close to the Dirac point.