Monte-Carlo simulations of thermal reversal in granular planar media

Abstract A general model is developed to simulate thermally agitated magnetization reversal in granular planar media. The modeled system is a two-dimensional hexagonal array with 40×40 grains. In this work, two systems were modeled; one consists of cobalt nanoparticles ( D =20 nm) with an average anisotropy coupling constant a (= KV/kT )=200, and another consists of FePt nanoparticles ( D =5 nm) with a =80. For both media, the time dependence of thermal coercivity at different array separations d is simulated. These simulations showed that interaction effects slow down the time variation of thermal coercivity.