Temperature dependence of the AMR curve in NiO/NiFe bilayers

Abstract The temperature dependence of the anisotropic magnetoresistance (AMR) curves was measured as a function of the angle between the applied field H and the exchange coupling field H ex in NiO(30 nm)/NiFe( t ) ( t =5, 10 and 30 nm) bilayers, and the data were compared with calculated results using the single-domain model with the crystalline anisotropy field as fitting parameter. The AMR curves for H ⩽ H ex are asymmetrical with respect to θ =0° in the t =10 nm sample, and the angles for maximum resistance, θ m , are located at the negative field region for the measurement temperature T =300 K. As temperature decreases, the AMR curve becomes nearly symmetric at T =100 K, and then again asymmetric with positive θ m . A comparison of these results with the calculated AMR has suggested that the crystalline anisotropy field increases with decreasing temperature, but its angle decreases.