Graphene spintronics: the role of ferromagnetic electrodes

TL;DR

This study uses first principles calculations to analyze spin transport at graphene-ferromagnet interfaces, revealing high spin efficiencies and spin-dependent energy gaps that influence spin currents.

Contribution

It provides new insights into spin filtering mechanisms at graphene-ferromagnet interfaces using first principles simulations.

Findings

Achieved spin efficiencies of 80% with Co and 60% with Ni electrodes.

Identified spin-dependent energy gaps of 0.4-0.5 eV at the K points.

Found that minority spin band gaps are higher in energy, leading to dominant minority spin currents.

Abstract

We report a first principles study of spin-transport under finite bias through a graphene-ferromagnet (FM) interface, where FM=Co(111), Ni(111). The use of Co and Ni electrodes achieves spin efficiencies reaching 80% and 60%, respectively. This large spin filtering results from the materials specific interaction between graphene and the FM which destroys the linear dispersion relation of the graphene bands and leads to an opening of spin-dependent energy gaps of roughly 0.4-0.5 eV at the K points. The minority spin band gap resides higher in energy than the majority spin band gap located near the Fermi level, a feature that results in large minority spin dominated currents.