R&D: Micromagnetic Simulation of L10-FePt-Based Exchange-Coupled-Composite-Bit-Patterned Media with MAMR at Hhgh Areal Density

Micromachines has published an article written by Pirat Khunkitti, Department of Electrical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002, Thailand, Naruemon Wannawong, Seagate Technology (Thailand) Co., Ltd., Nakhon Ratchasima 30170, Thailand, Chavakon Jongjaihan, Apirat Siritaratiwat, Anan Kruesubthaworn and Arkom Kaewrawang, Department of Electrical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002, Thailand.

Abstract: “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.“