Self-organized Co/Pt nanoparticulate arrays offer a novel approach to fabricating magnetic recording media with the potential for supporting Terabit/in.2 recording densities. Protein-derived Co/Pt nanoparticles are prepared within apoferritin from aqueous reactants, with synthesis conditions controlling grain size, structure, and composition. Smooth films on glass disk substrates are produced by either spin coating or dip coating from aqueous dispersions of the precursor material. Films are typically annealed at 590 °C for 60 min with a 19 kPa (190 mBar) partial pressure of H2 to form the L10 phase. By varying the annealing conditions we are able to produce coercivities in the range of 500–8000 Oe. Electrical testing of Co/Pt nanoparticulate media using a contact test recorder shows that these nanoparticle films are capable of sustaining recording densities of more than 12.6 Gbits/in.2 (143.6 kfci, kilo flux changes per inch). In this article we will present results from finished films with regard to film structure, magnetic properties, and recording capabilities.

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Modeling and experimental results are presented for keepered longitudinal recording media and planar (undershoot-reduced) thin film recording heads with low flying heights for areal densities >1 Gb/in.2. The keeper layer is magnetically coupled to the medium magnetic transitions, reducing the transition demagnetization and narrowing the transition length by about 10% in the media after recording. The reproduced bias field and the transition fields combine in the keeper to produce a partially saturated region, thereby modifying the fields from the medium transitions at the head during playback. We present experimental data on the write and read process for keepered media. Boundary element model results are presented which explain the amplitude gain and pulse asymmetries observed experimentally. Use of a keepered medium allows areal density improvements >20% through higher bits per inch.

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