R&D: Improvement of Dual-Layer HAMR Recording Conditions Using SMR

IEEE Transactions on Magnetics has published an article written by Yasuaki Nakamura, Madoka Nishikawa, Graduate School of Science and Engineering, Ehime University, Matsuyama, Japan, Simon John Greaves, RIEC, Tohoku University, Sendai, Japan, Yasushi Kanai, Deptment of Engineering, Niigata Institute of Technology, Kashiwazaki, Japan, and Yoshihiro Okamoto, Graduate School of Science and Engineering, Ehime University, Matsuyama, Japan.

Abstract: “Three-dimensional heat-assisted magnetic recording (3D-HAMR) with dual-recording layers (DL-HAMR) aims to achieve high areal density by using two conventional recording layers on one disk surface and reading simultaneously with an MR head. However, in conventional magnetic recording (CMR)-based DL-HAMR, the track width on the bottom layer is narrowed due to the track width limitation on the top recording layer, and the track on the top layer is also limited to prevent the information on the bottom layer from being erased. To address these issues, this study introduces shingled magnetic recording (SMR) into the DL-HAMR system. A simulation is carried out using a FePt granular medium with dual-layer structure. A two-pass write process with a Gaussian heat source was used, and the magnetization patterns were evaluated. SMR provided patterns close to the ideal track width for both layers. Furthermore, the medium signal-to-noise ratio (SNR) was measured, yielding 10.3 dB for CMR and 14.2 dB for SMR. The results show that the application of SMR improved the recording conditions of DL-HAMR compared with the CMR method, and the medium SNR increased by approximately 3.9 dB.“