R&D: HAMR Performance Impact from In-Plane Grains Variation

IEEE Xplore has published, in 2024 IEEE 35th Magnetic Recording Conference (TMRC) proceedings, an article written by Niranjan A. Natekar; Pierre-Olivier Jubert; Terry Olson; Alexander Goncharov; Richard Brockie; and Kiwamu Tanahashi, Western Digital Corporation, San Jose, CA, USA.

Abstract: “The technology development of Heat Assisted Magnetic Recording (HAMR) is a primary focus of both the industry and academia to ensure the HDD storage capacities follow the roadmap established by the Advanced Storage Research Consortium (ASRC). One important limitation arises from media noise, which results from structure or magnetic defects of the FePt grains that constitute the HAMR medium. This includes in-plane grains with easy axes pointing in-plane instead of out-of-plane. While the presence of these grains has been established in literature through experiments, there is a lack of understanding of how these grains can impact the HAMR performance. In this modeling study, we focus on the impact of in-plane grains specifically on the HAMR performance, by varying their proportion throughout the media and capturing the pre-channel and post-channel performance parameters. We extend this analysis using the THMap process to understand the effect of in-plane grains on room temperature switching (RTS), magnetization variance and the readback signal variance. Additionally, we compare the signal, noise, low frequency SNR (LF SNR) and jitter captured through micro magnetic simulations with values obtained from an analytical grain counting model. Finally, we explore ways to alleviate the impact of in-plane grains by optimizing media parameters and identifying the sensitivity for each media parameter.“