We present first-principles calculations of the magnetic hyperfine fields H-hf of 5sp impurities on the (001), (111), and (110) surfaces of Ni. We examine the dependence of H-hf on the coordination number by placing the impurity in the surfaces, on top of them at the adatom positions, and in the bulk. We find a strong coordination dependence of H-hf, different and characteristic for each impurity. The behaviour is explained in terms of the on-site s-p hybridization as the symmetry is reduced at the surface. Our results are in agreement with recent experimental findings.
We present ab initio calculations for spin injection in Fe-ZnSe and Fe-GaAs(001) systems, with and without detection by a second Fe lead. We consider the case of hot injection, as well as the presence of a tunneling barrier at the interface. Our calculations are valid in the ballistic regime. We find that these systems can be very efficient spin filters, leading to current spin polarizations and magnetoresistance ratios very close to the ideal 100%.
We report systematic first-principles calculations for ordered zinc-blende compounds of the transition metal elements V, Cr, and Mn with the sp elements N, P, As, Sb, S, Se, and Te, motivated by a recent fabrication of zinc-blende CrAs, CrSb, and MnAs. They show a ferromagnetic half-metallic behavior for a wide range of lattice constants. We discuss the origin and trends of half-metallicity, present the calculated equilibrium lattice constants, and examine the half-metallic behavior of their transition element terminated (001) surfaces.
We calculate the current spin polarization and the interface resistance of Fe/GaAs and Fe/ZnSe (001) spin injection junctions from first principles, including also the possibility of a Schottky barrier. From our results of interface resistance we estimate the barrier thickness needed for efficient spin injection if the process is nonballistic.
Department of Physics National and Kapodistrian University of Athens University Campus GR-157 84 Zografou, Athens