Giant magnetoresistance without defect scattering

The ballistic transport properties of magnetic metallic multilayers are studied using calculations based on the local-spin-density approximation in which the s electrons and the d electrons, usually held responsible for conduction and magnetism, respectively, are treated on an equal footing. A giant magnetoresistance of up to 120% is calculated for point contacts of Co/Cu multilayers. The effect can be explained as a slowing down of the s electrons by hybridization with d electrons which are strongly reflected and partially localized by the spin-dependent interface potentials. The method should be a useful instrument in a systematic search for new materials for magnetoresistive applications.