Dephasing-Induced Stabilization of a Perfectly Conducting Channel in Disordered Graphene Nanoribbons with Zigzag Edges

TL;DR

This paper demonstrates that pure dephasing can stabilize a perfectly conducting channel in disordered zigzag graphene nanoribbons, preventing conductance decay due to weak intervalley scattering and enabling quasi-quantized conductance over longer lengths.

Contribution

It reveals that dephasing effects can counteract the destabilization of the PCC caused by weak intervalley scattering in disordered graphene nanoribbons.

Findings

Dephasing suppresses conductance decay in disordered graphene nanoribbons.

Quasi-quantized conductance g ~ 1 is observable over a wide range of system lengths.

Dephasing enhances the stability of the perfectly conducting channel against Anderson localization.

Abstract

Electron transport in a disordered graphene nanoribbon with zigzag edges is crucially affected by a perfectly conducting channel (PCC), which is stabilized if intervalley scattering is ignorable. In the presence of such a PCC, the dimensionless conductance g of the system decreases to the quantized value of g = 1 with increasing system length L. In the realistic case where intervalley scattering is weak but not ignorable, the PCC is gradually destabilized with increasing L, and g eventually decays to zero owing to the onset of Anderson localization. Here, we show that such destabilization of the PCC can be relaxed by pure dephasing. We numerically calculate g in the presence of long-range impurities, which induce weak intervalley scattering, taking the dephasing effect into account. It is demonstrated that, under sufficient dephasing, the decay of g in the regime of g \lesssim 1 is strongly suppressed and the quasi-quantization of g (i.e., g ~ 1) can be observed in a wide region of L.