LOCAL-FIELD AND QUANTUM EFFECTS FOR CURRENT PERPENDICULAR TO PLANES IN MULTILAYERS

The calculation of giant magnetoresistance and in general, of electron transport for multilayers in the case of current perpendicular to the planes (CPP) requires both the two-point conductivity and the solutio n to the local field problem. In this paper we present a solution to t he local field problem at an interface using two approaches. In the fi rst approach we find the semiclassical solution for the local field wh en there is a band mismatch between two sides of an interface, and exa mine the deviation of the total resistance from the result of ''self-a veraging,'' in the lowest order of the value of the potential step. In the second approach, we solve for the quantum correction to the local field through a numerical iterative scheme. The oscillations due to t he quantum correction are surprisingly large, but their correction to the total resistance is remarkably small. Our results imply that the ' 'self-averaging'' of the resistance, which is usually assumed in analy sis of CPP, is only approximate. (C) 1997 American Institute of Physic s.