Magnetization reversal of Nd-Fe-B thin film under a nano-second pulse magnetic field

The magnetization reversal process of Nd-Fe-B magnets has been long discussed. Since the elemental steps of the magnetization reversal process such as a nucleation of reversed embryo and a wall depinning are the events as small as nano-meter scale and as fast as nano/subnano-second time scale, the study on the magnetization reversal with these space and time regions are essentially important. In this work, a generation of large amplitude nano-second pulse field and a fabrication of Nd-Fe-B nanodot were examined, and then the magnetization reversal process of the Nd-Fe-B nanodot under the nano-second pulse field was investigated. Combination of a Blumlein transmission line and a micro-coil enables to generate a pulse field of 0.87 T in amplitude and 6 ns in width. It was clearly demonstrated that the reversed domain evolution in the dot under the pulse field was quite different from that under the static field, probably owing to the dispersion of energy barrier of each elemental magnetization reversal step.