Dependence of Magnetoresistance and Antiferromagnetic Coupling on Growth Orientation and Interface Roughness in Epitaxial Co/Cu Superlattices

Epitaxial Co/Cu superlattices with surface orientations of (111), (100) and (110) were grown by ultrahigh-vacuum-based dc magnetron sputter deposition to investigate the dependence of magnetoresistance (MR) on growth orientation. The MR and antiferromagnetic (AFM) coupling were distinctly different in the superlattices of the three types even when prepared under the same conditions. The roughness of Co/Cu interfaces was found to be the largest in the (111) samples and the smallest in the (110) samples. A tendency for the MR and AFM coupling to decrease with decreasing interface roughness was observed in each of the three surface orientations. However, the order of magnitude of the MR ratio could not be explained in terms of the interface roughness alone.