MR Properties and Thermal Stabilities of Cu/Co/Cu/NiFe Multilayers

Cu/Co/Cu/NiFe multilayer films prepared by evaporation in an ultrahigh vacuum showed induced ferrimagnetism and giant MR properties. The slope of the linear part of the MR curve near zero field is sensitive to the coercive force and squareness ratio of magnetization of the NiFe layers. The maximum slope was 0.41 %/Oe for Cr(50Å)[Cu (50Å)/Co(10Å)/Cu(50Å)/NiFe(15Å)]×10. The annealing temperature dependence of the slope was due to the interdiffusion of NiFe and Cu layers. Improved thermal stability was obtained by the use of thicker NiFe layers.