A model of the properties of colloidal dispersions of weakly interacting fine ferromagnetic particles

A Monte Carlo technique has been used to simulate the magnetic properties of a colloidal dispersion of weakly interacting fine ferromagnetic particles. The initial susceptibility is shown to obey a Curie-Weiss like law in its variation with temperature. The ordering temperature in the Curie-Weiss law is found to increase with the diameter of the particles, the increase being associated with an increase in the local order in the system. Data from the Monte Carlo simulation is also used to assess the effects of interactions on the determination of particle size parameters from magnetic measurements. Investigation of the spatial correlation within the system reveals evidence of field induced particle agglomeration.