Computed hysteresis behavior and interaction effects in spheroidal particle assemblies

A three-dimensional hysteresis model for particulate recording media is described. The model consists of a particle assembly with a few hundred particles and includes particle shape effects (oblate or prolate spheroids), particle anisotropy distribution, particle position/orientation variation and magnetostatic particle interactions. The total magnetization of the assembly is computed dynamically, integrating the Landau-Lifshitz-Gilbert differential equation, in combination with a self-consistent iterative approach. On one hand, lateral interactions are dominant in prolate particle assemblies and different packing fraction has a marginal influence on the interaction effects. On the other hand, axial interactions are dominant in oblate particle assemblies and different packing fraction has a substantial influence on the interaction effects