SEMICLASSICAL THEORY OF PERPENDICULAR TRANSPORT AND GIANT MAGNETORESISTANCE IN DISORDERED METALLIC MULTILAYERS

The effect of disordered interfaces and bulk impurities on perpendicul ar transport in metallic multilayers is considered in an effective-mas s semiclassical approximation. The transmission matrix is obtained by diagrammatic perturbation theory in terms of the effective-mass and co nduction-band profiles at the interface. In the weak-scattering limit specular and diffuse scattering give equally important contributions t o the conductance. Predictions for the transport properties of interfa ces with low concentrations of strongly scattering defects should be a ccessible to verification by experiments. The transition from fully ba llistic (Sharvin) to diffuse transport (Drude) is described analytical ly both in two- and three-dimensional systems, where the former case i s of relevance for transport in the two-dimensional electron gas in se miconductor heterostructures. The theory is applied to the spin-valve effect in magnetic multilayers. The magnetoconductance is described by a simple formula in terms of the mean free path for the majority- and minority-spin electrons.