Rough edges in quantum transport of Dirac particles

Abstract

We consider Dirac particles confined to a thin strip, e.g., graphene nanoribbon, with rough edges. The confinement is implemented by a large mass in the Hamiltonian or by imposing boundary conditions directly on the graphene wave-functions. The scattering of a rough edge leads to a transverse channel-mixing and provides crucial limitation to the quantum transport in narrow ribbons. We solve the problem perturbatively and find the edge scattering contribution to the conductivity, which can be measured experimentally. The case of Schroedinger particles in a strip is also addressed, and the comparison between Schroedinger and Dirac transport is made. Anomalies associated with quasi-one dimensionality, such as Van Hove singularities and localization, are discussed. The violation of the Matthiessen rule is pointed out.