Conductance and giant magnetoconductance of Co vertical bar Cu vertical bar Co spin valves: Experiment and theory

We present measurements of the conductance and magnetoconductance,cl as a function of cobalt layer thickness for cobalt-copper-cobalt spin valves deposited by magnetron sputtering,a. 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 but spin-dependent scatter inp within the cobalt layers and possibly some channeling of electrons in the copper layer. We find that the transmission and reflection of electrons al the interfaces are strongly spin dependent and that it is not necessary to invoke additional diffuse spin-dependent scattering al the interfaces to explain the conductance and magnetoconductance of these samples.