Theory of giant magnetoresistance in granular alloys

A theory of giant magnetoresistance in granular alloys was developed by con sidering the spin-dependent scattering within the magnetic granules and at their boundaries and the continuous distributions of granule sizes and dire ctions of magnetization. The CPP formalism was recovered in the limit when the effective conductivities in the granules are much larger than the matri x conductivity. When this condition is not satisfied, the transport propert ies of the granular alloys derive from the crossover of the parallel and pe rpendicular current configurations. [S0163-1829(99)10309-6].