A PNR study of the off-specular scattering during the asymmetric magnetization reversal in an exchange-biased Co/CoO multilayer

We report on the observation of the effects of exchange bias on the magnetization reversal processes in a [Co/CoO/Au]20 system using polarized neutron reflectometry (PNR). The focus in this study is the investigation of the off-specular scattering of neutrons from magnetic domain structures during the magnetization reversal. In a previous PNR study on the same system, an asymmetry in magnetization reversal has been observed on opposite sides of the same hysteresis loop. For the decreasing field branch, the reversal was found to be dominated by domain wall motion of domains directed parallel or antiparallel to the applied field. In contrast, the reversal on the increasing field branch was characterized by rotation of magnetization. A significant loss of intensity was found for the specular reflected neutrons, while off-specular scattering experiments reveal that this magnetization reversal is not determined by coherent rotation but rather by a breaking up into smaller domains with different orientations.