Domain Dynamics Study using Magneto-Optical Microscope Magnetometer(MOMM) with 400-nm Spatial Resolution.

A magneto-optical microscope magnetometer (MOMM) has been developed to grab the domain reversal patterns in real time under applying a magnetic field, as well as, to simultaneously measure the local magnetic properties with 400-nm spatial resolution. Using the system, the domain reversal behavior is revealed to change contrastingly between wall-motion and nucleation dominant with changing the multilayer structure of Co/Pd multilayers. From a quantitative analysis, the reversal ratio of the wall-motion speed over the nucleation rate is a governing parameter for the contrasting domain reversal dynamics. The activation volumes of the wall-motion and nucleation processes are found to be unequal, and the difference is closely related with the domain dynamics. Based on a Monte-Carlo simulation, both the macroscopic magnetic properties and the local magnetic variation are responsible for the contrasting domain reversal behavior.