Graphite and graphene as perfect spin filters

TL;DR

This paper predicts perfect spin filtering at interfaces between graphite or graphene and certain nickel or cobalt surfaces, which is robust against roughness and disorder, enabling efficient spin injection for spintronic applications.

Contribution

It introduces a theoretical prediction of perfect spin filtering at graphite/metal interfaces based on lattice and electronic structure matching, with practical strategies to prevent bonding issues.

Findings

Perfect spin filtering predicted at graphite/metal interfaces.

Spin filtering insensitive to roughness and disorder.

Method to prevent chemical bonding issues with Cu dusting.

Abstract

Based upon the observations (i) that their in-plane lattice constants match almost perfectly and (ii) that their electronic structures overlap in reciprocal space for one spin direction only, we predict perfect spin filtering for interfaces between graphite and (111) fcc or (0001) hcp Ni or Co. The spin filtering is quite insensitive to roughness and disorder. The formation of a chemical bond between graphite and the open $d$-shell transition metals that might complicate or even prevent spin injection into a single graphene sheet can be simply prevented by dusting Ni or Co with one or a few monolayers of Cu while still preserving the ideal spin injection property.