  Transport properties of magnetic multilayers in current perpendicular to the
plane of the layers geometry are defined by diffusive scattering in the bulk of
the layers, and diffusive and ballistic scattering across the interfaces. Due
to the short screening length in metals, layer by layer treatment of the
multilayers is possible, when the macroscopic transport equation (Boltzmann
equation or diffusion equation) is solved in each layer, while the details of
the interface scattering are taken into account via the boundary conditions.
Embedding the ballistic and diffusive interface scattering in the framework of
the diffusive scattering in the bulk of the layers is the unifying idea behind
the problems addressed in this work: the problem of finding the interface
resistance in the multilayered structures and the problem of current-induced
magnetization switching.
