Domain configurations and reversal dynamics in Co-based nanomultilayers

Domain configurations and reversal behaviors in Co-based nanomultilayers have been quantitatively investigated. A sharp transition of domain configuration from a large-area domain pattern to a striped domain configuration with increasing the Co-sublayer thickness has been experimentally observed. The transition was well explained by an analytic theory based on calculating the magnetostatic energy in the multilayered structure by solving Maxwell's equations in continuum approximation. The transition was found to be ascribed to a competition between the magnetostatic energy and the domain-wall energy. Magnetization reversal dynamics in Co-based nanomultilayers has been investigated by the magnetization viscosity measurement and the real-time domain observation. The reversal behaviors were sensitively changed from wall-motion dominant to nucleation dominant with either increasing the Co-sublayer thickness or increasing the number of repeats. Quantitative analysis revealed that the contrasting reversal behavior was mainly caused by the sensitive change in the wall-motion speed. The reversal ratio of the wall-motion speed to the nucleation rate was found to be an important parameter to characterize the reversal behavior in these systems.