Alternating and rotational hysteresis losses of γ-Fe2O3powders in a nonmagnetic matrix

Some aspects of the alternating and rotational hysteresis losses of very diluted samples of γ-Fe
2
O
3
particles are examined. The packing fraction
p
of the particles ranges from 0.001 to 0.120. The coercive force is found to be independent of
p
. The alternating and rotational hysteresis losses appear dependent upon
p
for
p < 0.04
; the rotational losses increase considerably as
p
approaches zero. The values of the rotational hysteresis integral are close to the theoretical ones corresponding to the model of magnetization reversal of chain of spheres with fanning, but they increase slightly with decreasing
p
for
p < 0.04
. Generally, the ratio of rotational to alternating losses is about twice that for bulk materials. All these effects are ascribed to a weakening of the magnetic interactions among particles.