Regensburg 2004 – wissenschaftliches Programm

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PV: Plenarvorträge

PV XIV

PV XIV: Plenarvortrag

Freitag, 12. März 2004, 09:15–10:00, H1

Assault on storage density of 1 Terabit / sq-in and beyond — •Dieter Weller — Seagate Research, 1251 Waterfront Place, Pittsburgh PA 15222, U.S.A.

The areal density in magnetic recording has surpassed ∼50 Gbit/in² in products and ∼100 Gbit/in² in laboratory demonstrations. These densities have been achieved with recording media comprised of Co-alloy nanostructured materials with horizontal orientation of the magnetization (longitudinal recording). Grain sizes are 8-10 nm and grain size distributions are near 20% (sigma over mean). Going much beyond 100 Gbit/in² requires magnetically harder materials with smaller, thermally stable grains (5–8 nm) and tighter distributions (<15%). Experiments indicate that this may be possible in perpendicular recording, where a soft magnetic imaging layer is used to enhance the write field, enabling such grains to be recorded on. Basic technology demonstrations of about 110 Gbit/in² have already been reported and modeling suggests that extensions to about 1 Tbit/in² should be possible using that technology. Going much beyond Tbit/in², however, will require more drastic changes of heads and media. One of the fundamental limitations relates to the media sputter fabrication process, which may not allow the tight grain size and magnetic dispersions required in models. So called self-organized magnetic arrays (SOMA) of chemically synthesized FePt nanoparticles are being explored as alternatives. These structures do not only show extremely tight size distributions (<5%) but are also magnetically much harder than current Co-alloys. Writing will require temporal heating and cooling in a magnetic field (HAMR: Heat-Assisted Magnetic Recording). It is envisioned, that a combination of SOMA and HAMR may once lead to single particle per bit recording, with ultimate densities near 50 Tbit/in² (10 yrs storage time, ambient temperature, FePt type anisotropies).