Darren Karns

HAMR Areal Density Demonstration of 1+ Tbpsi on Spinstand

Heat-assisted magnetic recording (HAMR) is being developed as the next-generation magnetic recording technology. Critical aspects of this technology, such as plasmonic near-field transducer (NFT) and high anisotropy granular FePt media, have been demonstrated and reported. However, progress with areal density was limited until recently. In this paper, we report a basic technology demonstration (BTD) of HAMR, at 1.007 Tbpsi with a linear density of 1975 kBPI and track density of 510 kTPI, resulting from advances in magnetic recording heads with NFT and FePtX media. This demonstration not only shows significant areal density improvement over previously reported HAMR demos, more significantly, it shows HAMR recording at a much higher linear density compared to previous reports. It is an important milestone for the development of such a new technology. Many challenges still remain to bring this technology to market, such as system reliability and further advancement of areal density.

The effect of media background on reading and writing in perpendicular recording

The effect of stray fields from the recording layer on the reading and writing process has been studied for a perpendicular recording system. The system consists of a single pole writer with a wide return pole, a conventional spin-valve reader and a double layer recording medium. A writer- and reader-induced asymmetry is observed in the recording process for a dc erased background. The asymmetry is interpreted as stray fields of the dc background giving rise to reader saturation and an offset in the current driven inductive write field.

Effect of gradient alignment in heat assisted magnetic recording

Heat assisted magnetic recording (HAMR) is one of the leading technologies to extend magnetic storage. Significant progress has been achieved in head and media fabrication [M. Seigler et al., IEEE Trans. Magn. 44, 119 (2008); Y. Peng et al., TMRC, Seagate Research, 2008], resulting in a basic technology demonstration (C. Hardie et al., ODS Conference Proceedings, 2008) of HAMR. Both field and field-gradient limitations of a conventional perpendicular recording are overcome by engineering the thermal profile (notably the gradient) and recording at a temperature near Tc (thus requiring a smaller head field). We have used a micromagnetic recording model to study the effect of thermal and field-gradient alignment in HAMR by varying the separation between the thermal spot and the leading edge of the head field. The output of the recording model includes transition jitter, which is based on Monte Carlo simulations of isolated transitions. We use a realistic granular medium with HK∼50–80 kOe and a grain size of ...

Perpendicular recording near 100 Gb/in/sup 2/

Theoretical analyses have projected perpendicular recording capable of achieving ultimate areal densities greater than longitudinal recording systems. For perpendicular recording to supplant longitudinal recording, laboratory demonstrations will need to be made which intercept or exceed the areal densities achieved by state-of-the-art longitudinal recording demonstrations. Recent demonstrations have come close to eliminating the gap between these technologies. In this paper, recording experiments at areal densities in the 60 to 100 Gb/in/sup 2/ range will be described. It will be shown that the head field from conventional single-pole writers is not well localized to the data track and that if the media do not have sufficiently high nucleation thresholds, this fringe field will gradually erase data on the adjacent track if the track pitch is too aggressive. Extension of this technology to densities of the order of 1 Tb/in/sup 2/ will require heads that reduce the extent of the fringe field without sacrificing available on-track field.