Influence of size and surface on magnetism of magnetite and maghemite nanoparticles

The study of the influence of the size of magnetite and maghemite clusters on the magnetic properties (magnetic moment and the Curie temperature, the blocking temperature, etc.) is performed. For separating by size, the magnetic separation and centrifugation of the aqueous solution of iron oxide nanoparticles were applied. Native particles and the particles covered with a bioresorbable layer were examined. The controlled change in the nanoparticles' size leads to a change in their Curie temperature and magnetic moment. The theoretical calculations of the magnetic properties were made by using the Monte Carlo method for the classical Heisenberg model with different bulk and surface magnetic moments.