Tuning the magnetic field sensitivity of planar Hall effect sensors by using a Crspacer layer in a NiFe/Cr/IrMn trilayer structure

Abstract

Planar Hall effect (PHE)-based magnetic field sensors have recently received considerable attention due totheir fascinating properties. For the NiFe/spacer/IrMn trilayer PHE sensor structures, tuning the exchange bias via aspacer layer is very crucial due to its direct effects on the sensor’s magnetic field sensitivity. Here the effect of Cr spacerlayer thickness on PHE sensitivity and exchange bias is investigated in NiFe (10 nm)/Cr (tCr)/IrMn (20 nm) trilayerstructures where the tCrvaried between 0.0 nm and 1 nm with a step of 0.1 nm. As the tCrincreased, we observed afast decrease in exchange bias field. When the thickness of Cr spacer layer increased up to 0.7 nm, a maximum sensitivityof 4.4V/(OemA) was obtained. Besides, sensor voltage exhibited ±100 nV noise level. With this noise level, a 1.6T magnetic field resolution was achieved.