Role of interfacial roughness in the giant magnetoresistance in Co/Cu superlattices

We have measured both the magnetization and the temperature dependence of the giant magnetoresistance (GMR) in Co/Cu superlattices with different interfacial roughness. The magnetization dependence of the magnetoresistance (MR) has precluded the existence of a strong spin dependence in the potential not only for the bulk but also for the interfacial scattering. The temperature dependence of the GMR is hardly influenced by the interfacial roughness, while the residual resistivity changes significantly. The residual MR ratio decreases with increasing interfacial roughness. This reveals that the spin-dependent s-d scattering in the bulk is crucial for the GMR in Co/Cu superlattices. The interfacial roughness mainly contributes to the residual resistivity, and the spin dependence in the scattering at interfaces weaker than that in the bulk.