INTERACTION AND DIMENSIONAL EFFECTS IN MICROMAGNETIC MODELS

In this article the effects of dipolar and exchange interactions on th e remanence ratio and coercivity in granular solids are examined using a generalized three-dimensional Monte Carlo model. This model allows the final configuration of magnetic moments to be calculated as a func tion of concentration, temperature and magnetic field. The results sho w that for a system of polydispersed grains having their anisotropy ax es oriented at random, both the remanence ratio and coercivity increas e with increasing exchange interaction. In addition the magnetization loops exhibit regions where the reversal slows down and gives rise to distinct quasi-bimodal behavior. These effects are due to the fact tha t the exchange interactions are not uniform throughout the system. Thi s model can account for many features observed in a wide range of real materials. (C) 1997 American Institute of Physics.