Theory of giant magnetoresistance in magnetic granular systems

Abstract
We present an explanation of the giant magnetoresistance observed in some magnetic granular solids as well as magnetic multilayers by considering spin-dependent s-s and/or s-d scattering. We obtain an explicit expression for the magnetoresistance of magnetic granular solids. This expression relates the giant magnetoresistance to the microscopic quantities and geometric parameters, and is in agreement with the experimental data. We also address a few relevant aspects of experiments.