Micromagnetic Simulation of L1₀-FePt-Based Exchange-Coupled-Composite-Bit-Patterned Media with Microwave-Assisted...

In this work, we propose exchange-coupled-composite-bit-patterned media (ECC-BPM) with microwave-assisted magnetic recording (MAMR) to improve the writability of the magnetic media at a 4 Tb/in² recording density. The suitable values of the applied microwave field's frequency and the exchange coupling between magnetic dots, A_dot, of the proposed media were evaluated. It was found that the magnitude of the switching field, H_sw, of the bilayer ECC-BPM is significantly lower than that of a conventional BPM. Additionally, using the MAMR enables further reduction of H_sw of the ECC-BPM. The suitable frequency of the applied microwave field for the proposed media is 5 GHz. The dependence of A_dot on the H_sw was additionally examined, showing that the A_dot of 0.14 pJ/m is the most suitable value for the proposed bilayer ECC-BPM. The physical explanation of the H_sw of the media under a variation of MAMR and A_dot was given. Hysteresis loops and the magnetic domain of the media were characterized to provide further details on the results. The lowest H_sw found in our proposed media is 12.2 kOe, achieved by the bilayer ECC-BPM with an A_dot of 0.14 pJ/m using a 5 GHz MAMR.