Reversal pathway dependent asymmetric recovery effect in polycrystalline FeNi/FeMn bilayers

Abstract

For the exchange biased polycrystalline FeNi/FeMn bilayers, we systematically studied the ferromagnet (FM) magnetization reversal pathway dependent recovery effect of training using a vector vibrating sample magnetometer. Our experimental results show unambiguously that the well-known recovery effect strongly depends on the FM magnetization reversal pathway in addition to the final FM magnetization orientation. If the FM magnetization rotates in two opposite directions, i.e., clockwise (CW) or counter clockwise (CCW), to the same final FM magnetization orientation, the recovery effect exhibits distinct asymmetry. For the present initial magnetization configuration, only the CW pathway induces recovery effect, whereas it is impossible to produce training recovery through the CCW pathway. This recovery asymmetry can be explained by considering the random distribution of antiferromagnetic grains' easy axes and the FM magnetization reversal history as well.