Theoretical studies of the field-cooled and zero-field cooled magnetization of interacting fine particles

We have applied a Monte–Carlo model of the properties of an interacting fine particle system to calculations of the field-cooled (FC) and zero-field cooled (ZFC) magnetization. The variation of Tg, the temperature peak, in the ZFC is also calculated. For an interacting system the effective energy barrier distribution is dependent on the packing density, and this is reflected in the Tg vs H curve. An important result is the demonstration that magnetostatic interactions between the particles can give rise to a peak in the FC magnetization. This is in agreement with experiments and is a result of the magnetic order introduced by the magnetostatic interactions.