Magnetoresistance Investigations in Exchange-Biased IrMn/NiFe Bilayers

Magnetoresistance measurements have been employed to demonstrate the thermal evolution of exchange bias, reversal asymmetry and training effect in ion-beam sputtered IrMn/NiFe bilayers. Magnetoresistance investigations have shown a significant increase in exchange bias field and coercivity, pronounced reversal asymmetry and, most prominently, a strong training effect all occurring at low temperature (T < 50 K). These experimental results are attributed to the occurrence of temperature dependent crossover from uniaxial to biaxial anisotropy in the IrMn layer.