Simulation of magnetic aftereffect in particulate recording media

Employing a numerical integration of the Landau-lifshitz-Gilbert equation for phenomena with nanosecond characteristic times and a Monte Carlo method for much longer time periods, the authors have developed a method that in practice allows efficient simulation of magnetic aftereffect in an assembly of interacting particles for any time length of practical interest. Each particle is assumed to behave according to the Stoner-Wohlfarth model with its easy axis pointing in an arbitrary direction; thus the reversible component of magnetization change is incorporated in magnetic aftereffect studies. This simulation method was implemented on a workstation, and the hysteresis loops of the granular Fe(SiO₂) thin film material with a sweep time of 10 minutes were calculated with magnetic aftereffect. The thermal broadening of a demagnetization-limited written transition was simulated for the same material. After a sharp transition was created in the center of an assembly of particles, the change in the transition width over 100 seconds was studied