Presentation Information
[P1-51]Demagnetization Processes in Nd-Fe-B sintered and Ferrite Magnets derived from magnetic measurement and soft X-ray magnetic circular dichroism microscopy
*Yutaka Matsuura1 (1. Research Institute for Applied Sciences (Japan))
Keywords:
Nd-Fe-B sintered magnet,ferrite magnet,demagnetization,coercivity,coercivity mechanism
Demagnetization processes of Nd-Fe-B sintered and ferrite magnets were investigated via magnetic measurements and soft X-ray magnetic circular dichroism microscopy (XMCD). From the alignment dependence, the coercivities of these magnets were determined by magnetic domain wall motion because it decreased with improved alignment. The alignment dependence of coercivity varies according to the compositions and manufacturing methods due to the cluster sizes of demagnetization grains at their coercivity. The sizes increased with decreasing temperature and varied with composition. The continuous small demagnetization was observed in the recoil curve in a demagnetization field smaller than their coercivity. From XMCD, the magnetization reversal of individual particles was observed in a small demagnetization field, and clusters of demagnetization grains were formed from reversals of neighboring particles at the discretely demagnetized particle near its coercivity. The cluster growth yielded coercivity, and it was speculated that cluster sizes were related to their alignments and angular dependences of their coercivities. They also depended on the number of discretely demagnetized particles that occurred in a smaller demagnetization field than their coercivity.
