Monolayer Assembly and Fixation of FePt Nanoparticles: Microstructure and Magnetic Properties

Monolayer-FePt nanoparticles/boron carbide-matrix composite thin films on Si substrate were fabricated by a two-step method. Scanning electron microscopy indicates that the 6 nm FePt nanoparticles are well-separated in the monolayer with an average interparticle distance of <3 nm. Transmission electron microscopy demonstrates that under high temperature annealing, the FePt nanoparticle monolayer possesses good thermal stability against particle sintering. A coercivity of 2200 Oe is obtained for the Fe 47 Pt 53 nanoparticle film. The results indicate that the boron carbide could serve as an effective stopper to the FePt grain growth and aggregation and thus contribute to the particle size uniformity and the perseverance of the particle monolayer morphology of the composite film after the high temperature annealing.