Kinetic Monte Carlo approach to modeling thermal decay in perpendicular recording media

A procedure is developed to study the evolution of high anisotropy magnetic recording media due to thermally activated grain reversal. It is assumed that the system is composed of single domain grains that evolves by passing through a sequence of relatively long-lived metastable states punctuated by abrupt reversals of individual grains. Solutions to the rate equations describing the sequence of metastable states are calculated using kinetic Monte Carlo. Transition rates are formulated from the Arrhenius-N\'eel expression in terms of the material parameters, temperature, and applied field. Results obtained from this method are shown to be in good agreement with those calculated from finite-temperature micromagnetics. The method is applied to study the rate dependence of finite-temperature $MH$ loops and the thermal degradation of a recorded bit pattern in perpendicular recording media. A significant advantage of the procedure is its ability to extend simulations over time intervals many orders of magnitude greater than is feasible using standard finite-temperature micromagnetics with relatively modest computational effort.