  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.

Mesoscale and Nanoscale Physics;Materials Science