Soft underlayer magnetization dynamics

A micromagnetic model for the writing process in perpendicular magnetic recording is developed to study the effect of the soft underlayer on the dynamic reversal of the recording layer. The upper part of the soft material is discretized micro-magnetically, each spin following LLG dynamics; the remaining part has infinite permeability. The validity of the model is tested in the static case. Dynamically, high-frequency spin motion is observed in the soft layer. Nevertheless, the field inside the data layer follows the time dependence of the input waveform.