Resistance of multilayers with long length scale interfacial roughness

Abstract

The resistance of multilayers with interfacial roughness on a length scale large compared to the layer spacing is obtained using the Boltzmann equation. Both the current-perpendicular-to-plane (CPP) and current-in-plane (CIP) geometries are considered in the limits where the mean-free paths are short and long compared to the atomic spacing. In the short mean-free path limit, the resistance decreases in the CPP geometry and increases in the CIP geometry. In the long mean-free path limit, the resistance increases in both configurations due to enhanced surface scattering. The giant magnetoresistance can either be enhanced or reduced by roughness depending on the sample parameters. Estimates of the short and long mean-free path effects in Fe/Cr multilayers are obtained using experimentally determined parameters.