Conductance and giant magnetoconductance ofCo|Cu|Cospin valves: Experiment and theory

Abstract

We present measurements of the conductance and magnetoconductance as a function of cobalt layer thickness for cobalt-copper-cobalt spin valves deposited by magnetron sputtering. We compare these measurements to calculations of the conductance and magnetoconductance, which are based on first-principles calculations of the self-consistent electronic structure of the cobalt-copper-cobalt system. The calculations are performed using a generalized Kubo formula for the nonlocal layer dependent conductivity, which is implemented within the layer Korringa-Kohn-Rostoker method for electronic-structure calculations. The scattering rates within each layer are adjusted phenomenologically to be consistent with the experimentally observed resistivity of thick films of cobalt and copper. The magnetoconductance and its dependence on the thickness of the cobalt layer are consistent with calculations that include strong bulk spin-dependent scattering within the cobalt layers and possibly some channeling of electrons in the copper layer. We find that the transmission and reflection of electrons at the interfaces are strongly spin dependent and that it is not necessary to invoke additional diffuse spin-dependent scattering at the interfaces to explain the conductance and magnetoconductance of these samples.