Spin injection: materials specific theory

Summary form only given. The huge scientific and technological impact of spin-transport in metallic materials has stimulated attempts to study it in semiconductors. The difficulties encountered can be explained in terms of a resistor model in which the small spin-dependent resistivity of typical ferromagnetic metals is completely dominated by the large spin-independent resistivity of the semiconductor. This model neglects the spin-dependent interface resistance caused by band mismatch of the two materials, known to be important in GMR. We calculate the spin-dependence of the interface resistance between ferromagnetic metals (such as Fe) and compound semiconductors (such as InAs) from first-principles whereby specular and diffuse scattering are treated on an equal footing. We focus here on the special case of Fe/InAs which forms an ohmic contact and so should work at low bias voltages. We also consider CaB/sub 6/, a semiconductor with a band gap of 0.8 eV, and the effect of La doping. Magnetism in La/sub x/Ca/sub 1-x/B/sub 6/ is found to occur just on the metallic side of a Mott transition in the La-induced impurity band.