Numerical simulations of quasistatic remagnetization processes in fine magnetic particle systems

Various numerical methods used for simulation of quasistatic remagnetization processes in interacting systems of fine single-domain magnetic particles are analyzed. Among them methods based on the sequential alignment of magnetic moments along the effective field are found to be the fastest, especially in the most interesting case of a small single particle anisotropy when cooperative remagnetization modes play a dominant role. Further it is shown, that the random field approximation (RFA) which is often used to take the interparticle interaction effects into account is valid for large particle anisotropies only. The distribution density of the interaction field is found to transform from the Lorentzian to the Gaussian form with the increasing particle volume fraction. Finally hysteresis loops for a wide range of single-particle anisotropy values and particle concentration are calculated and the crossover from the single particle to the collective behavior with decreasing single particle anisotropy is investigated.