Henrik Siegle

Effect of Anisotropy Influences on the Angle Dependent Resistance Changes in IrMn Spin-Valves

Giant magneto-resistance (GMR) effect in a spin-valve has a uni-directional or cosine dependence when rotated in an applied magnetic field; however, anisotropy effects cause deviations from this cosine dependence. The influence of uniaxial anisotropy in the free layer and Anisotropic Magneto-Resistance (AMR) were studied on the angle dependent resistance changes in IrMn spin-valves. The uniaxial anisotropy component was analyzed by changing the anisotropy axis from parallel to perpendicular to the bias direction in different sample sets. The deviation due to AMR was determined by changing the current direction from parallel to perpendicular to the bias direction in separate rotation measurements. The results indicated that the uniaxial anisotropy had no influence on the angle dependent resistance change while AMR added a cosine-squared resistance signal to the overall resistance change. A discrepancy between experiment and theory of the AMR influence was seen with use of a simple simulation. Ferromagnetic interlayer coupling is identified as a possible cause for this difference between theory and experiment.