Reversal mechanism and suppression of training in an exchange-coupled system

We show that the extent of training in exchange-biased systems can be strongly influenced by the field cooling procedure. This phenomenon is revealed by comparing the behavior of the system in two different magnetic configurations: cooling the system in a remanent state without an external magnetic field (state I) results in a suppression of the training effect, whereas the same sample being field cooled (state II) exhibits a clear training response. Interestingly, by cooling the sample in a critical field HFC close to the coercive field HC of the ferromagnet, we find a peculiar situation with a coexistence of states I and II. By using a depth-sensitive polarized neutron reflectivity technique, we can establish a clear correlation of the reversal mechanism with either the untrained or trained state.