Ferromagnetism as a universal feature of inorganic nanoparticles

Room-temperature ferromagnetism is exhibited by nanoparticles of a variety of inorganic materials although they are intrinsically non-magnetic. Typical of such nanomaterials are the oxides, CeO2, TiO2, Al2O3, and MgO. Nanoparticles of nitrides such as GaN and chalcogenides such as CdS and CdSe also exhibit ferromagnetism. Ferromagnetism of the nanoparticles is confined to the surface. This phenomenon has been utilized to render the classic ferroelectric BaTiO3 to be multiferroic wherein surface ferromagnetism coexists with bulk ferroelectricity. Interestingly, nanoparticles of superconducting YBa2Cu3O7 show surface ferromagnetism. It is possible that surface ferromagnetism of inorganic nanoparticles can be usefully exploited.