Time-resolved Observation of Field-dependent Magnetization Reversal Behavior

Abstract

We report the experimental finding that there exists a transition of magnetization reversal process with varying

the applied field in Co/Pd multilayer. We have measured the wall-motion speed V and the nucleation rate R

during magnetization reversal via time-resolved direct domain observation, where the magnetization reversal

process of Co/Pd multilayer is found to take a transition from thermal activation process to viscous process at

the critical field of about 1.87 HC (coercivity). In the thermal activation regime, we find that the field dependences

of two activation volumes for the wall-motion process and the nucleation process are different with each

other, which reveals that the wall-motion and nucleation experience completely different interactions. In the viscous

regime, we find that the wall-mobility is much smaller than a typical value for the sandwiched Co films,

which implies that the Co/Pd interfaces in multilayer substantially contribute to the dynamic dissipation.