Composite Structure With Superparamagnetic Writing Layer for Heat-Assisted Magnetic Recording

Abstract

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 $1~\textrm {nm}\times 1~\textrm {nm}\times 1~\textrm {nm}$ renormalized parameters of FePt. Analytical derivation and micro-magnetic simulation results both show the volume dependence of the SPD: $\textrm {Width}\boldsymbol {\propto } 1/({\mathrm{ 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.