High density magnetic recording on protein-derived nanoparticles

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 ${\mathrm{H}}_2$ to form the ${\text{L1}}_0$ 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.