Field dependence of the activation volumes in Co/Pd multilayered films.

The field dependence of the activation volumes of nucleation and wall-motion processes in magnetization reversal of Co/Pd multilayers is presented, as observed using a magneto-optical Kerr-effect microscope capable of real-time domain imaging in a wide time range of 10-5-103 s. The analytic forms of the activation volumes are derived from a theoretical consideration of equilibrium conditions of the two typical domain evolution processes in a ferromagnetic film with uniaxial perpendicular anisotropy; the theory is shown to be in good agreement with the experimental results. It was found that the field dependence of the activation volumes can be characterized by the difference between the domain wall energy and the dipolar energy. [ABSTRACT FROM AUTHOR]