Recording Performance and Comparison of Graded- ${T_{c}}$ and - ${K_{u}}$ HAMR Systems

Heat-assisted magnetic recording (HAMR) signal-to-noise ratio results are presented based on Landau-Lifshitz-Bloch recording simulations using a double-layer composite T_c media. An exchanged-coupled-composite Ku media is also considered in a HAMR system. Mean T_c and σT_c are varied in conditions of high and low interlayer exchange coupling, using material parameters consistent with FePt. Results suggest that using a composite T_c media may potentially regain ~1-2 dB from a single layer HAMR system with dB loss of ~3 dB, varying cure temperature distributions up to 6%. However, some of the benefits are due to creating conditions of writing above T_c. A significant performance degradation is found to occur if grains are not heated strictly above the Curie temperature, in both single and double-layer media. And use of a K_u composite media beyond deploying a composite T_c media shows insignificant gain in the recording performance.