Theoretical prediction of perfect spin filtering at interfaces between close-packed surfaces of Ni or Co and graphite or graphene

摘要: The in-plane lattice constants of close-packed planes fcc and hcp Ni Co match that graphite almost perfectly so they share a common two-dimensional reciprocal space. Their electronic structures are such overlap in this space for one spin direction only allowing us to predict perfect filtering interfaces between (111) or (0001) Co. First-principles calculations the scattering matrix show is quite insensitive amounts interface roughness disorder which drastically influence spin-filtering properties conventional magnetic tunnel junctions transition metals semiconductors. When single graphene sheet adsorbed on these open d-shell transition-metal surfaces, its characteristic structure, with topological singularities at K points Brillouin zone, destroyed by chemical bonding. Because bonds weakly Cu has no states Fermi energy point either spin, structure can be restored dusting few monolayers while still preserving ideal spin-injection property.