Ion Beam Stabilization of FePt Nanoparticle Arrays for Magnetic Storage Media

Abstract

We describe the use of ion beam induced crosslinking to harden the organic matrix material of self-assembled arrays of monodisperse (4 nm) FePt nanoparticles, providing diamondlike carbon barriers to inhibit agglomeration of the nanoparticles under heat treatment. Such stabilization is necessary for the particles to survive the >500°C annealing required for growth of the fct L10 phase of FePt, whose magnetic anisotropy is necessary for application of such arrays for high density recording. Selective area irradiation of continuous nanoparticle coatings, using ion beams patterned over a full disk by stencil mask or with ion projection optics, followed by dissolution of the unexposed coating, is proposed as a means of fabricating extended bit patterns consisting of isolated "islands" of FePt nanoparticles, with characteristic dimensions of tens of nanometers.