Effects of spacer layer thickness and substrate temperature on the magnetoresistance of rf-sputtered CoFe/Cu/NiFe trilayers

A study of the variation of the magnetoresistance in radio frequency magnet ron sputtered CoFe/Cu/NiFe tri-layered thin films with thickness t(Cu) and substrate temperature (T-s) is performed. The magneto resistance is measure d for fields applied parallel to the current at room temperature. The depen dence of the magneto resistance on tc indicates the presence of an oscillat ory interlayer exchange coupling through the t(Cu) layers with a period of about 1.1 nm. The magnetoresistance is increased as the substrate temperatu re is decreased. The increase in the magnetoresistance is considered to be caused by the improvement in the sharpness of interfaces. The result indica tes that the interfacial spin-dependent scattering is significant for the m agneto resistance in CoFe/Cu/NiFe spin valves.