Slow dynamics in perpendicular media

A computational study of the dynamic behavior of perpendicular media is presented. A Monte-Carlo model is used to investigate the magnetic properties and time dependence over long time scales. It is found that the switching field distribution determined from the recoil loops is strongly sensitive to the presence of exchange coupling, as is the effective demagnetizing factor, which is found to decrease rapidly with exchange coupling; an observation related to the increasing correlation length resulting from the exchange interactions. A hybrid model incorporating Landau-Lifshitz-Gilbert dynamics at time scales of the order of nanoseconds and a Monte-Carlo approach to the long time scale dynamics is also presented and applied in calculations of the time variation of the coercivity.