Dynamical properties of magnetization reversal in exchange-coupled NiO/Co bilayers - art. no. 172402

Real time dynamic magnetization reversal measurements at room temperature h ave been performed on polycrystalline exchange-coupled NiO/Co bilayers over 10 decades of applied field sweep rates. Domain wall displacement and doma in nucleation regimes govern the magnetization reversal at low and high swe ep rates, respectively. The crossover between the two regimes depends on th e relative thickness of the two layers. Thicker Co favors propagation, wher eas thicker NiO favors nucleation. The coupling energy at the interface was found to be inversely proportional to the square root of the area correspo nding to the activation (Barkhausen) volume. These results are consistent w ith a model of exchange anisotropy in which a randomness of the coupling al ong the ferromagnetic (F)/antiferromagnetic (AF) interface is combined with a thermally activated switching process of the AF magnetization.