MagnetoResistance of graphene-based spin valves

TL;DR

This paper investigates the magnetoresistance in graphene-based spin valves and finds that the magnetoresistance effect is very weak, suggesting limited performance for spintronic applications.

Contribution

It provides a theoretical analysis showing that graphene spin valves exhibit minimal magnetoresistance due to weak dependence on lead spin configurations.

Findings

Magnetoresistance in graphene spin valves is very small.

Graphene conductivity is insensitive to lead parameters.

Performance of graphene spin valves for spintronics is likely limited.

Abstract

We study the magnetoresistance of spin-valve devices using graphene as a non-magnetic material to connect ferromagnetic leads. As a preliminary step we first study the conductivity of a graphene strip connected to metallic contacts for a variety of lead parameters, and demonstrate that the resulting conductivity is rather insensitive to them. We then compute the conductivity of the spin-valve device in the parallel and antiparallel spin polarization configurations, and find that it depends only weakly on the relative spin orientations of the leads, so that the magnetoresistance $MR$ of the system is very small. The smallness of $MR$ is a consequence of the near independence of the graphene conductivity from the electronic details of the leads. Our results indicate that, although graphene has properties that make it attractive for spintronic devices, the performance of an graphene-based spin-valve is likely to be poor.