We present the optimized planar Hall resistance (PHR) obtained by using biaxial currents in a NiO (30 nm)/NiFe (30 nm) bilayers. The measured PHR, Rxy, had a drift resistance due to the intrinsic and extrinsic characteristics caused by magnetization and sample geometry, respectively. The drift voltage due to drift resistance restricted the PHR ratio and could be compensated for by using the auxiliary current Ix for the sensing current Iy to enhance PHR ratio. A huge PHR ratio over 3000% (±1500%) with the linearity and small hysteresis for the magnetic field experimentally obtained using biaxial currents and could be explained by the anisotropic characteristic of the magnetoresistance, which is influenced by the exchange coupling field (Hex) induced by the antiferromagnetic NiO layer.

Articles you may be interested inDetermination of rotatable anisotropy in exchange-biased bilayers using anisotropic magnetoresistance technique J. Appl. Phys. 93, 7714 (2003); 10.1063/1.1558191 Angular dependence of magnetization reversal process in exchange coupled ferromagnetic/antiferromagnetic bilayers J. Appl. Phys. 93, 3422 (2003); 10.1063/1.1554760 Field dependent anisotropic magnetoresistance measurements on CoFe/IrMn bilayersThe uniaxial anisotropy field H K and angle ␥ from exchange coupling field in anisotropic magnetoresistance sample has been analyzed on the basis of the rotational magnetization of single domain. The anisotropy field H K in bilayer NiO͑30 nm͒/NiFe(t) obtained from the measured magnetoresistance profiles at magnetizing angle ϭ0°and 90°from the exchange coupling field changes from positive to negative as the thickness of NiFe increases, transition at about 20 nm. The anisotropy field ͉H K ͉, and angle ␥ show a minimum values at the transition thickness, which is the optimum thickness in anisotropic magnetoresistance sample design in order to increase the field sensitivity and reduces hysteresis loss.