Magnetic properties of iron nanoparticles coated by silica shell

We have studied the properties of iron nanoparticles coated by silica layer, which were prepared using surface capping agents. Such designed silica layer prevents the oxidation of the iron cores and promotes the self-organization of nanoparticles into the 1D chain structures. The particular superferromagnetic state was observed in studied material. Peculiar magnetic properties of 1D arranged composite consisting of Fe nanoparticles coated by insulating SiO₂ layer were studied. Silica layer promotes the self-organization of 4 nm iron nanoparticles to the chain-like structures. Magnetization study shows that prepared nanoparticles exhibit very strong inter-particle magnetic interactions, which lead to long-range ordering of nanoparticles magnetic moments. Magnetic properties show superferromagnetic behaviour. The low value of room temperature coercivity, the existence of electrical insulating silica layer and small size of iron nanoparticles favour studied material for potential usage in microelectronic devices designed for high voltage frequencies. (authors)