Thermal hysteresis of magnetization in NiFe/IrMn exchange-biased ferromagnet

Abstract

Abstract Magnetization reversal in NiFe/IrMn exchange-biased thin films was investigated under thermal cycling in an external magnetic field, applied opposite to the direction of the exchange bias field. Thermal hysteresis of magnetization accompanied by changes in magnetization polarity was observed in the applied field close to the exchange bias value. This effect appears when thermally induced variations of the exchange bias exceed the corresponding variations in coercivity. The amplitude of magnetization reversal in NiFe/IrMn structures exceeds ∼100 times the corresponding amplitude in spin-crossover molecular compounds. The observed bistability of the magnetic state, revealed by thermal hysteresis, gradually disappears with an increase in the number of cooling–heating thermal cycles, that indicates an irreversible quenching of the interfacial magnetization configuration. This effect paves the way for the creation of a new class of switching devices with thermally assisted bistability in the ferromagnetic state.