'Band structure' and electrical conductivity of disordered layered systems

Employing the Kubo-Greenwood formula, the electrical conductivity of disordered layered systems is formulated in terms of the (screened) Korringa-Kohn-Rostoker method and the coherent potential approximation. It is shown that the elements of the electrical conductivity tensor can be described in terms of 'layer-diagonal' and 'layer-off-diagonal' contributions. In order to discuss effects of the underlying electronic structure on the electrical conductivity, but also to point out particular contributions to it, Bloch spectral functions are formulated. A spin-polarized (relativistic) application of the present theory to non-collinear disordered magnetic multilayers allows one to discuss giant magnetoresistance (GMR) on an ab initio level in quite a general context.