Nearly Perfect Single-Channel Conduction in Disordered Armchair Nanoribbons

TL;DR

This paper demonstrates that disordered armchair graphene nanoribbons exhibit nearly perfect single-channel conduction at low energies due to internal wavefunction phase structures, despite the presence of impurities and inter-valley scattering.

Contribution

It reveals the mechanism behind near-perfect conduction in disordered armchair nanoribbons and classifies them into the orthogonal universality class regardless of impurity range.

Findings

Single-channel conductance is nearly perfect despite disorder.

Backward scattering matrix elements vanish in the lowest order.

Multi-channel conductance decays exponentially with length.

Abstract

The low-energy spectrum of graphene nanoribbons with armchair edges (armchair nanoribbons) is described as the superposition of two non-equivalent Dirac points of graphene. In spite of the lack of well-separated two valley structures, the single-channel transport subjected to long-ranged impurities is nearly perfectly conducting, where the backward scattering matrix elements in the lowest order vanish as a manifestation of internal phase structures of the wavefunction. For multi-channel energy regime, however, the conventional exponential decay of the averaged conductance occurs. Since the inter-valley scattering is not completely absent, armchair nanoribbons can be classified into orthogonal universality class irrespective of the range of impurities. The nearly perfect single-channel conduction dominates the low-energy electronic transport in rather narrow nanorribbons.