Effect of substrate temperature and insertion of layers on CoFe/Cu/NiFe spin valve trilayers

The effects of substrate temperature, CoFe insertion layer and NiFe insertion layer on the giant magnetoresistance are reported for radio-frequency magnetron sputtered CoFe/Cu/NiFe spin valve tri-layered films. It is found that the room temperature magnetoresistance decreases when the substrate temperature increases. This is attributed to the fact that the interfacial spin-dependent scattering weakens because the diffusion at the interface increases at higher deposition temperature. The magnetoresistance increases when CoFe layers are inserted at the Cu/NiFe interfaces and the magnetoresistance decreases when NiFe layers are inserted at the CoFe/Cu interfaces. This implies that a smooth and continuous interface is more easily obtained in CoFe/Cu than in NiFe/Cu interface. Smooth interfaces strengthen the interfacial spin-dependent scattering that increases the giant magnetoresistance.