The Role of Media Damping in a Perpendicular Recording System

This paper discusses the role of media damping for a perpendicular recording system that uses a realistic head field and media parameters in a micromagnetic model based on the Landau-Lifshitz-Gilbert formulation for the magnetization dynamics. The modeling approach uses pulsed write fields of varying pulse duration to record footprints of the head on the media. Using a criterion that 95% of the grains are reversed in the footprints, we calculate the field needed to record as a function of pulse duration, i.e., the dynamic coercivity. As shown in a previous paper, we find two distinct regions in the dynamic coercivity plots. The thermally dominated (long time) region can be described by appropriately including the demagnetization effects in the thermal stability factor K_uV/k_BT. The short time (dynamic) behavior shows a precipitous increase in the required recording field accompanied by an increase in the erase width. The latter effect causes the recording performance to degrade, especially in the short time dynamic regime. The onset of dynamic effects strongly depends on the media damping. In order to achieve high data and high areal density, we need to optimize damping in the recording heads and media.