Composite structure with superparamagnetic writing layer for heat-assisted magnetic recording

In conventional heat-assisted magnetic recording media, the recording layer also acts as the storage layer. To minimize the effect of Tc variance, a new composite structure with a superparamagnetic writing layer is proposed to decouple the recording problem from the long-term storage issue. The thermal switching probability distribution (SPD) was calculated using 1nm × 1nm × 1nm renormalized parameters of FePt. Analytical derivation and micro-magnetic simulation results both show the volume dependence of the SPD Width ∞ 1/(Volume)^1/2. The SPD of the composite structure designed in this paper has a full-width half-maximum of 44 K, which is 20% narrower than that found in an FePt recording layer subject to 3% Tc variance.