Size effect on the magnetism of nanocrystalline Ni films at ambient temperature

Size effect on the magnetization and the coercivity of nanocrystalline Ni films has been examined at room temperature. Agreement between modeling predictions and measurements reveals that the size-suppressed magnetization results from the drop of spin–spin exchange energy due to the coordination number (CN) imperfection of atoms near the surface edges, and that the size-enhanced coercivity arises from intergrain interaction that is proportional to the inverse of particle size. Findings herewith and reported previously on the size-induced lattice contraction and Curie temperature suppression evidence the significance of atomic CN imperfection on the unusual behavior of a ferromagnetic nanosolid.