R&D: Two Articles on HAMR Technologies

R&D: Vector Recording, Advancing Areal Density in HAMR with Innovative Read Head Design

Authors propose novel read head design to detect the magnetic field both perpendicular (with a conventional reader) and parallel (with a vector reader) to the surface of recording layer.

IEEE Transactions on Magnetics has published an article written by Kamal Hosen, Department of Electrical and Computer Engineering, University of Minnesota Twin Cities, USA, M. F. Erden, Seagate Technology, MN, USA, and R. H. Victora, Department of Electrical and Computer Engineering, University of Minnesota Twin Cities, USA.

Abstract: “The hard disk drive (HDD) industries necessitate substantial data storage capacity, and to meet this challenge, they are investigating innovative technologies such as heat-assisted magnetic recording (HAMR). In HAMR, it is feasible to write higher KBPI (kilo bits per inch) and KTPI (kilo tracks per inch) to achieve a greater areal density capacity (ADC) of around 4 Tb/in2. However, the existing reader architecture restricts the increase in BPI and TPI, as it requires scaling down the reader dimension to read data with a smaller bit length and narrower track width. Recently, two-dimensional magnetic recording (TDMR) has shown some ability in the reading process to increase ADC and relax reader scaling, but this improvement is not sufficient to address the data storage crisis. In this paper, we propose a novel read head design to detect the magnetic field both perpendicular (with a conventional reader) and parallel (with a vector reader) to the surface of the recording layer. We have also proposed alternative reader designs that can address limitations in biasing of the vector reader and are capable of performing similarly to that reader. Therefore, our newly designed reader architectures reduce the scaling issue of the reader dimension and are capable of recovering data with high TPI, thus achieving higher ADC.“

R&D: Computational Analysis of HAMR Media Noise with Multilayer Micromagnetic Media Model

Authors present a computational investigation of THMap metrics, especially the top and bottom edges of the THMap, to extract noise power magnitude.

IEEE Transactions on Magnetics has published an article written by Lei Xu; Vincent Le, Terry Olson, and Kiwamu Tanahashi, Western Digital Corporation, San Jose, CA, USA.

Abstract: “Heat-assisted magnetic recording (HAMR) media noise is a critical factor in determining HAMR recording performance. In this study, we employ an exchange-coupled multilayer media model to analyze the media noise. We present a computational investigation of THMap metrics, especially the top and bottom edges of the THMap, to extract noise power magnitude. We focus on the cap magnetic properties and interlayer vertical exchange coupling to evaluate their impact on the THMap metrics. We find that introducing the domain wall (“incomplete switching”) into a proper location of multilayer stack reduces the media noise. In parallel, we run recording simulations to relate THMap metrics to the recording performance. These results contribute to a better understanding of future HAMR media design.“