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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/in 2 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.

Current-perpendicular-to-the-plane giant magnetoresistance (CPP-GMR) read sensors based on Heusler alloys are promising candidates for ultrahigh areal densities of magnetic data storage technology. In particular, the thickness of reader structures is one of the key factors for the development of practical CPP-GMR sensors. In this research, we studied the dependence of the free layer thickness on the stability of the Co 2 (Mn 0.6 Fe 0.4 )Ge Heusler-based CPP-GMR read head for an areal density of 1 Tb/in 2 , aiming to determine the appropriate layer thickness. The evaluations were done through simulations based on micromagnetic modelling. The reader stability indicators, including the magnetoresistance (MR) ratio, readback signal, dibit response asymmetry parameter, and power spectral density profile, were characterized and discussed. Our analysis demonstrates that the reader with a free layer thickness of 3 nm indicates the best stability performance for this particular head. A reasonably large MR ratio of 26% was obtained by the reader having this suitable layer thickness. The findings can be utilized to improve the design of the CPP-GMR reader for use in ultrahigh magnetic recording densities.