Synthesis of magnetic CoPt/SiO2 nano-composite by pulsed laser ablation

Core–shell nanoparticles composed of ferromagnetic cobalt platinum cores covered by non-magnetic silica shells were synthesized by laser ablation of a composite target in a helium background gas. The average diameter of the CoPt core was controlled by adjusting the CoPt/SiO2 ratio of the ablation target and size-classifying the nanoparticles by an electrical mobility classifier. The present method successfully synthesized nearly monodispersed nanoparticles with an average core diameter as small as 2 nm. The size-dependent magnetic properties of nano-composite films generated by the deposition of nanoparticles onto the substrate were investigated by a SQUID magnetometer.