R&D: 317Gb/in2 Recording Areal Density on Strontium Ferrite Tape

IEEE Transactions on Magnetics has published an article written by Simeon Furrer, Patrick Ebermann, Mark A. Lantz, Hugo Rothuizen, Walter Haeberle, Giovanni Cherubini, Roy D. Cideciyan, IBM Research-Zurich, CH-8803 Rüschlikon, Switzerland, Shinji Tsujimoto, Yoshihiro Sawayashiki, Noriko Imaoka, Yuto Murata, Tomohide Ueyama, Yoichi Akano, Tetsuya Kaneko, Hodaka Suzuki, Masashi Shirata, Kenji Naoi, Takashi Koike, Hiroaki Doshita, Recording Media Research Laboratories, FujiFilm Corporation, Odawara 250-0001, Japan.

Abstract: “The recording performance of a new prototype magnetic tape based on perpendicularly oriented strontium ferrite particles is investigated using a 29 nm wide tunneling magnetoresistive reader. At a linear density of 702 kbpi, a post-detection byte-error rate of 2.8e-2 is demonstrated based on measured recording data and a software read channel. The read channel uses a 64-state implementation of an extended version of a data-dependent noise-predictive maximum-likelihood detection scheme that tracks the first and second order statistics of the data-dependent noise. At the demonstrated post-detection byte-error rate, a post-error-correction-coding byte-error rate of less than 1e-20 can be achieved using an iterative decoding architecture. To facilitate aggressive track-density scaling, we made multiple advances in the area of track following. First, we developed a new timing-based servo pattern and implemented a novel quad channel averaging scheme. Second, we developed a new field programmable gate array prototyping platform to enable the implementation of quad channel averaging. Third, we enhanced our low disturbance tape transport with a pair of 20 mm diameter air bearing tape guides and a prototype track-following actuator. Fourth, we developed a novel low friction tape head and finally, we designed a set of tape speed optimized track-following controllers using the model-based H∞ design framework. Combining these technologies, we achieved a position error signal (PES) characterized by a standard deviation ≤ 3.18 nm over a tape speed range of 1.2 to 4.1 m/s. This magnitude of PES in combination with a 29 nm wide reader enables reliable recording at a track width of 56.2 nm corresponding to a track density of 451.9 ktpi, for an equivalent areal density of 317.3 Gb/in².“