Co nanoparticle monolayer prepared by multiple diffusive incorporations onto a pre-existing nanoparticle template

A monolayer of Co nanoparticles was fabricated on a polyimide (PI) film by successively depositing a 3.5-nm-thick Co thin film on top of a pre-existing nano-sized Ni particle template. Each Co deposition was followed by thermal annealing to induce coalescence of the Co film onto the pre-existing Ni seed particles. The Co deposition/thermal annealing step was repeated up to three times to grow 7–10-nm-sized Co nanoparticles on a polyimide film. We demonstrate that the average particle size can be controlled by the number of Co depositions. Thus-produced Co nanoparticles exhibited saturation magnetization comparable to its bulk value with coercivity reaching up to 120 Oe. Such a nanoparticle template process presented here can be easily extended to a ternary alloy particle and multi-functional nanoparticle system for potential applications in nanomagnet arrays, nanophotonic arrays or nanocatalyst arrays.