Spin-dependent scattering and giant magnetoresistance

We consider the origins of the spin-dependent scattering which is believed to be responsible for the giant magnetoresistance effect. We argue on the basis of first-principles calculations of the electronic structure, magnetic moments, and electrical resistivities that this spin-dependent scattering originates largely from the tendency of spin-dependent atomic potentials to 'match' in one of the spin channels of magnetic alloys or multilayers. We also argue that the matched channel will tend to have a lower density of states at the Fermi energy. Both of these effects will contribute to the GMR. We argue that there is the potential for a very large GMR in an ideal system, but that spin-independent scattering possibly coming from misaligned spins near the interfaces prevents its observation.