The Boltzmann equation is solved for a system consisting of alternating ferromagneticnormal metallic layers. The in-plane conductance of the film is calculated for two configurations: successive ferromagnetic layers aligned (i) parallel and (ii) antiparallcl to each other. The results explain the giant negative magnetoresistance encountered in these systems when an initial antiparallel arrangement is changed into a parallel configuration by application of an external magnetic field. The

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... ion depends on (A) geometric parameters (the thicknesses of the layers); (B) intrinsic metal parameters (number of conduction electrons, magnetization and effective masses in the layers); (C) bulk sample properties (conductivity relaxation times); and (D) interface scattering properties (diffuse scauering versus potential scattering at the interfaces). lt is found that a large negative magnetoresistance requires, in general, considerable asymmetry in the interface scattering for the two spin orientations. Ali qualitative features of the experiments am reproduced. Quantitative agreement can be-achieved with sensible values of the parameters. The effect can be conceptually explained based on considerations of phase.space availability for an electron of a given spin orientaOon as it travels through the multilayer sample in the various configurations and traverses the interfaces,