Quantum blockade and loop current induced by a single lattice defect in graphene nanoribbons

TL;DR

This paper theoretically studies how a single defect in graphene nanoribbons can induce quantum blockade and loop currents, affecting conductance and controllability based on defect position and ribbon properties.

Contribution

It reveals the impact of a single lattice defect on conductance and current patterns in graphene nanoribbons, highlighting controllability via defect placement.

Findings

Defect-induced conductance dips can reach zero at certain Fermi energies.

Loop currents develop around the defect during conductance dips.

Conductance behavior depends on defect position, severity, and ribbon edges.

Abstract

We investigate theoretically the electronic transport properties in narrow graphene ribbons with an adatom-induced defect. It is found that the lowest conductance step of a metallic graphene nanoribbon may develop a dip even down to zero at certain values of the Fermi energy due to the defect. Accompanying the occurrence of the conductance dip, a loop current develops around the defect. We show how the properties of the conductance dip depend on the parameters of the defect, such as the relative position and severity of the defect as well as the width and edges of the graphene ribbons. In particular, for metallic armchair-edges graphene nanoribbons, whether the conductance dip appears or not, they can be controlled by choosing the position of the single defect.