Fluctuation fields in perpendicular media

In this paper, we used a micromagnetic model to examine the influence of the grain size dispersion and the distribution of easy axes on activation volume (V_act) and the shape of the fluctuation field (H_f) versus m curve. Simulations of a granular magnetic medium were carried out using a micromagnetic model based on the Landau-Lifshitz-Gilbert equation, including a random field term to represent thermal fluctuations. The results show that the factors which influence the shape of the H_f versus m curves for granular perpendicular media are; the angular distribution of easy axes, the average grain size and the width of the grain size distribution.