Direct observation of magnetization reversal behaviors in exchange-coupled NiO/Fe films

We have investigated the magnetization reversal behavior in exchange-coupled NiO/Fe films with varying the NiO thicknesses using a magneto-optical microscope magnetometer capable of direct domain observation in real time. Interestingly enough, the magnetization reversal mechanism is gradually changed from a domain wall-motion process to a nucleation process as the NiO thickness increases. This result clearly demonstrates that the exchange coupling effect between the NiO and Fe layers increases the domain wall pinning effect of the Fe layer, resulting in the nucleation reversal mode. (C) 2010 American Institute of Physics. [doi:10.1063/1.3340457]