Magnetism of nanocrystalline materials

Nanocrystalline solids are materials consisting of small crystallites (typically 1–10 nanometers). These materials have a high proportion of atoms located in the interfacial regions between the crystallites. Therefore their magnetic properties are strongly determined by the interfaces. In this work we present Mössbauer studies carried out on various nanocrystalline materials. Beneath the normal crystalline component the Mössbauer spectra clearly indicate the existence of an component with modified magnetic properties which corresponds to the interfaces in this type of material. For nanocrystalline α-Fe an enhancement of the hyperfine field was observed in the interfacial component at low temperatures, whereas a decrease was found for nanocrystalline Ni.