Abstract
The rotaional hysteresis loss Wr was measured for M-type hexagonal strontium ferrite (SrM) fine particles with different average particles diameters and coercive forces HcCJ. The relationship between HcCJ, Wr, the distribution of anisotropy field HA and the rotational hysteresis integral Rh, as well as milling effects were examined. The distribution of HA of SrM fine particles was improved by annealing. Wr/Ms curves expanded to the low magnetic field as increasing milling time, because of increased distribution of HA, even though Hc, remarkably decreased. The effective HA was in proportion to He, in SrM fine particles that had less milling effects. As HcCJ increased the rotaional hysteresis integral Rh decreased, and the magnetization switching approachs the coherent rotation mode.
