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 bia xial currents in a NiO (30 nm)/NiFe (30 nm) bilayers. The measured PHR, R-x y, had a drift resistance due to the intrinsic and extrinsic characteristic s caused by magnetization and sample geometry, respectively. The drift volt age due to drift resistance restricted the PHR ratio and could be compensat ed for by using the auxiliary current I-x for the sensing current I-y to en hance 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 o f the magnetoresistance, which is influenced by the exchange coupling field (H-ex) induced by the antiferromagnetic NiO layer. (C) 2000 American Insti tute of Physics. [S0021-8979(00)02219-2].