Hysteresis effects of varying concentrations of magnetite,hematite, pyrrhotite,and greigite grains in a diamagnetic matrix

Summary The hysteresis properties of synthetic samples with very low contents of hematite, pyrrhotite, greigite and admixtures of magnetite and hematite in a diamagnetic matrix have been studied. The diamagnetic matrix used was sodium chloride (NaCl). The contents of the magnetic minerals varied for hematite from 0.5 to 6 wt%, for pyrrhotite from 0.02 to 0.2 wt% and for greigite from 0.02 to 0.6 wt%. Diamagnetic contributions to the magnetization curves can be distinguished in the measured samples. We observed a non-linear dependence of coercivity and saturation magnetization upon increasing contents of hematite as a result of effects of both the diamagnetic matrix and the hematite content. Only the saturation remanence which is measured in a zero magnetic field has a linear dependence on the hematite concentration. The shape of the hysteresis curves of admixtures of magnetite and hematite are probably caused by magnetostatic interactions.