ELECTRONIC-STRUCTURE AND TRANSPORT-PROPERTIES IN MAGNETIC SUPERLATTICES

The microscopic origin of the giant magnetoresistance in metallic superlattices is ascribed to spin-dependent random exchange potential caused by roughness of the interfaces. The random exchange potential is determined self-consistently by calculating the electronic structure and magnetic moments near the interfaces for Fe/TM and Co/TM superlattices, where TM's denote the transition-metal elements. The tight-binding d-band model and recursion method are used in the calculation. The lifetime of electrons is estimated from the imaginary part of the self-energy produced by scattering of electrons by the random exchange potential. The material dependence of the magnetoresistance in Fe/TM and Co/TM superlattices is systematically studied and compared with the experimental results. An expression of the thermoelectric power is derived and its relation to the magnetoresistance is clarified. The material dependence of the thermoelectric power is also discussed.