Multiscale model of advanced recording system for enhancement of HAMR performance by FePt-based ECC media

Heat Assisted Magnetic Recording (HAMR) is a novel high-density magnetic recording technology that leverages thermal assistance during the writing process to achieve ultrahigh areal densities beyond 4 Tb/in². Optimizing both the writing process and the magnetic medium properties is crucial to realize this potential. In this work, we developed a multiscale approach based on the Landau-Lifshitz-Bloch (LLB) equation of motion parameterized using atomistic calculations. Atomistic simulation provide the required temperature dependent input quantities for the LLB equation. This multiscale approach makes it possible to accurately describe the physics of the magnetization dynamics at temperature close to the Curie point while overcoming the computational limitations of atomistic model when dealing with large systems. In this work, the model is employed to investigate an alternative exchange-coupled composite (ECC) medium structure composed of a hard FePt phase and a soft Fe-like material with a higher Curie temperature ( \\(T_{\\textrm{c}}\\) ) than FePt, aimed at enhancing HAMR performance. The advantage of the ECC system lies in its ability to achieve magnetization reversal by lowering the maximum temperature ( \\(T_\\textrm{max}\\) ) of the laser pulse. Using multiscale model that integrates atomistic and micromagnetic simulations, this study examines the magnetization reversal behavior during the recording process. For comparison, granular films composed of single grain FePt with high anisotropy and an ECC structure are simulated to investigate the switching probability ( \\(P_{SW}\\) ) of the writing process. We find that the ECC structure gives rise to an increase in switching probability. In particular, the ECC medium yields a \\(P_{SW}\\) of over 90% with a reduction in maximum temperature and pulse duration of 10% with respect to an FePt medium. The proposed ECC structure delivers significantly improved HAMR write efficiency, outperforming current FePt media and providing a viable pathway for next-generation high-density recording.