Stability studies of exchange bias field of Mn_(80)Ir_(20)/Co_(60)Fe_(20)B_(20) by network analyzer ferromagnetic resonance

摘要

The stability of the exchange bias field H_(eb) has been studied for Mn_(80)Ir_(20)/Co_(60)Fe_(20)B_(20) thin films by means of network analyzer ferromagnetic resonance. The results demonstrated that H_(eb) decreases with increasing temperature. The observed variation in the magnitude of H_(eb) and even a reversal in the sign of H_(eb) as a function of time above room temperature can be interpreted by a thermally activated reversal of antiferromagnetic domains as evidenced by the linear dependence of H_(eb) on In t according to the Neel-Arrhenius law. Moreover, the correlation between the reversal of antiferromagnetic domains and the antiferromagnetic grain volume is obtained.