Anisotropic magnetoresistance in CoO/Co and CoO/Fe bilayers in the biased and unbiased state

Magnetoresistance and magnetic hysteresis loop measurements have been used to investigate the strong interfacial coupling in cobalt oxide/ferromagnet bilayers at low temperatures. For the biased state, an asymmetry in the magnetization reversal processes has been found. It is characterized by domain wall motion as the dominant mechanism for the decreasing field branch and an appreciable amount of magnetization rotation for the increasing field branch. The observed behavior is different from other exchange bias systems.