This paper reports on the progress in developing self organized nanoparticulate arrays for magnetic recording at densities beyond 30 Gbit/cm2 (200 Gbit/in2), and in particular describes the beneficial use of biological templates in developing such arrays. Chemically synthesized, high magnetocrystalline anisotropy magnetic nanoparticles have demonstrated extremely narrow size distributions that are critical in reducing media noise. Due to their monodispersity, they also exhibit emergent self-patterning that could potentially support bit-per-particle densities up to 2–8 Tbit/cm2 (10–50 Tbit/in2).
High anisotropy L10 CoPt precursor grains 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- or dip-coating from aqueous dispersions of the precursor material. Films are typically annealed at 590 °C for 60 minutes with a 19 kPa (190 mBar) partial pressure of H2 to form the L10 phase.
We report on recently produced films that have demonstrated moderate-density recording using a contact drag tester with commercial, 0.35 μm-wide magnetoresistive (MR) heads. The highest areal density currently achieved for these nanoparticulate films is 0.93 Gbit/cm2 (6.0 Gbit/in2).