Investigation of Exchange Bias in Irmn/Nife Bilayer Thin Films Using Magnetoresistance Technique

Abstract

A bottom pinned Si/SiO2/Ta(20)/IrMn(15)/NiFe(10)/Ta(5) film has been fabricated using an ion beam sputtering system at room temperature. Post-deposition magnetic annealing was performed on sputtered multilayer thin film in a vacuum of 2´10-6 mbar at 250˚C for one hour in an in-plane magnetic field of 1.8 kG. The X-ray diffraction and X-ray reflectivity measurements have been performed for the structural and thickness analysis, respectively. The roughness of individual layers was determined using XRR measurements. The longitudinal MOKE measurements have been performed to measure the exchange bias, coercivity, and magnetic anisotropy at room temperature. The magnetoresistance measurement technique is employed to demonstrate the thermal evaluation of the exchange bias effect, training effect, and magnetization reversal asymmetry at room temperature and low temperature. The magnetoresistance measurement revealed a large exchange bias, pronounced magnetization reversal asymmetry, and enhancement in the training effects at 20 K. The experimental result exhibits the occurrence of temperature-dependent change from uniaxial to biaxial exchange anisotropy.