Magnetization of two-dimensional magnetic fluids

The influence of polydispersity on the magnetization of two-dimensional dipolar discs with short-range repulsive interaction is studied by means of Monte Carlo simulations and a high field approximation perturbation theory. Within the framework of perturbation theory an analytical expression is derived for the magnetization of monodisperse and polydisperse systems. The theoretical predictions are in good agreement with the corresponding Monte Carlo simulation data.