Thickness dependence of planar Hall resistance and field sensitivity in NiO(3Onm)/NiFe(t) bilayers

We measured the planar Nail resistance (PHR) profiles in NiO (30 nm)/NiFe (t) bilayers for t = 5, 10, 20 and 30 nm and analyzed its field sensitivity in terms of exchange-coupling field and anisotropy constant. The measured PHR shows linear field dependence at near H = 0 as well as small hysteresis. The linear field range Delta H and resistance change, Delta R = R-parallel to - R-perpendicular to decrease with the NiFe thickness, where Delta H is calculated to be proportional to the anisotropy constant K-u and exchange-coupling field H-ex. However, the field sensitivity Delta R/Delta H shows a maximum value at t = 20 nm; where K-u is the minimum. The PHR has the advantage of a linear response at the operating field range and can be used for a recording read-out head and related applications. (C) 2000 Elsevier Science B.V. All rights reserved.