Exchange coupled composite media for heat assisted magnetic recording

Micromagnetic simulation is used to calculate the temperature derivative of the switching field dHsw/dT for a composite media with a superparamagnetic writing layer. The results show that dHsw/dT is reduced for a defined probability of switching, and switching field line width remains almost unchanged. An analytical two-spin model is established to relate exchange coupling between the two layers Jex to energy barrier and the switching probability distribution (SPD). Both the analytical model and micro-magnetic simulation show that the full-width half-maximum FWHM∝(Jex)−0.5 and writing temperature Tsw∝(Jex)−1. It is also found that the writing layer leads the storage layer during switching.