Optimization of planar Hall resistance using biaxial currents in a NiO/NiFe bilayer: Enhancement of magnetic field sensitivity

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, R-xy, 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 I-x for the sensing current I-y 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 (H-ex) induced by the antiferromagnetic NiO layer. (C) 2000 American Institute of Physics. [S0021-8979(00)02219-2].