Resistance of multilayers with long length scale interfacial roughness
  The resistance of multilayers with interface roughness on a length scale which is large compared to the atomic spacing is computed in several cases via the Boltzmann equation. This type of roughness is common in magnetic multilayers. When the electronic mean free paths are small compared to the layer thicknesses, the current flow is non-uniform, and the resistance decreases in the Current-Perpendicular-to-Plane (CPP) configuration and increases in the Current-In-Plane (CIP) configuration. For mean free paths much longer than the layer thicknesses, the current flow is uniform, and the resistance increases in both the CPP and CIP configurations due to enhanced surface scattering. In both the CPP and CIP geometries, the giant magnetoresistance can be either enhanced or reduced by the presence of long length scale interface roughness depending on the parameters. Finally, the changes in the CPP and CIP resistivities due to increasing interface roughness are estimated using experimentally determined parameters. 
Jason Alicea and Selman Hershfield