Reduced magnetization in magnetic oxide nanoparticles

Magnetic oxide nanoparticles have been studied to elucidate the effects of nanoscale finite size on the magnetic behavior of the particles. Magnetite nanoparticles synthesized by coprecipitation show superparamagnetism at room temperature with reduced saturation magnetization MS. The MS value decreases and approaches zero with decreasing particle size. Yttrium iron garnet (YIG) nanoparticles also show a similar trend. The magnetization of nanoparticles estimated using the Langevin function with the particle size distribution indicates that the reduced magnetization can be consistently explained by the existence of a spin-disordered surface layer with the thickness of 1–2nm. The results found in magnetite and YIG nanoparticles suggest that the reduced magnetization can be commonly observed among magnetic oxide nanoparticles due to the existence of spin disordered surface layer.