SEMICLASSICAL TRANSPORT-THEORY OF INHOMOGENEOUS SYSTEMS

Based on the probability-conserved Boltzmann equation, we develop a fo rmal and general transport theory for the conductivity in inhomogeneou s systems. In particular, we show that the local current density insid e the sample can be expressed as a boundary value integral, so that th e local electric field need not be calculated explicitly. The theory i s first applied to multilayer systems and shown to recover the previou s theory. More importantly, by including spin-dependent interface scat tering and bulk scattering, we employ our theory successfully to accou nt for the giant magnetoresistance in magnetic granular systems.