Electronic conductance of twisted bilayer nanoribbon flakes

TL;DR

This paper investigates the electronic conductance of twisted bilayer graphene nanoribbons, revealing that low-energy transport is dominated by edge states localized in AB stacking regions, with conductance largely unaffected by lead positioning.

Contribution

It introduces a detailed analysis of transport in twisted bilayer graphene flakes, highlighting the role of edge states and their localization in conductance behavior.

Findings

Low-energy conductance is governed by edge states with AB stacking.

Conductance is insensitive to lead position due to state localization.

Edge states have reduced weight at junctions, affecting transport.

Abstract

We study the transport properties of a twisted bilayer graphene flake contacted by two monolayer nanoribbons which act as leads. We analyze the conductance in terms of the spectra of the bilayer nanoribbon and the monolayer contacts. The low-energy transport properties are governed by the edge states with AB stacking. Remarkably, the electronic conductance in this energy region does not depend much on the relative position of the leads, in contrast with that of bilayer flakes with more symmetric stackings. We attribute this feature to the localization of these low-energy states in the AB edge regions of the flake, having a much smaller weight at the junctions between the flake and the nanoribbon leads.