MAGNETIC AFTEREFFECTS OF CO-γ-Fe₂O₃ FINE PARTICLES

Magnetic aftereffect constant, Sv, and rotational hysteresis integral, Rh, of CO-γ-Fe2O3 particles, whose particle mean volume, V, is especially fine, and of VHS tapes produced on a trial basis using these particles were measured for a comparative study with those of metal and Ba-ferrite. The activation volume, v, calculated from Sv and Hc had a relationship of Hc ∼v-0.67. V/v was approximately 4. The results were nearly the same as those with metal particles. CO-γ-Fe2O3 and metal particles showed the trends by which the more v and V/v decreased, the closer the coherent rotation mode became. In the case of Ba-ferrite, as Hc increases Rh decreases, to gradually approach the coherent rotation mode. The mechanism of magnetization reversal have a close relationship with v and V.