Monte-Carlo calculation of the coercive force and phase transitions in ensembles of Stoner-Wohlfarth particles with exchange interactions

Abstract

A Monte-Carlo (MC) method is used to study the magnetization of an ensemble of Stoner-Wohlfarth particles with interparticle interactions of a ferromagnetic type. A modification of the procedure for the MC calculation is proposed to speed up the calculations. The magnetization of the ensemble is studied at different temperatures and for different ratios of the exchange field of the interparticle interaction and the uniaxial magnetic anisotropy field of the particles. It is shown that Neel relaxation has a significant influence on the coercive properties of the ensemble if the interparticle exchange field does not exceed the anisotropy field of the particles. It is also found that, at low temperatures, the coercive properties of Stoner-Wohlfarth particles with exchange interactions are related to the loss of stability of the orientation of the average magnetic moment vector of the particles. At high temperatures, the coercivity of the particle ensemble is associated with the complete loss of stability of the superferromagnetic state. The critical fields and critical temperatures for an ensemble of Stoner-Wohlfarth particles with exchange interactions are analyzed.