Size-dependent magnetic properties of nanocrystalline yttrium iron garnet powders

Yttrium iron garnet (YIG) powders with particle sizes of 9, 14, 25 and 60nm have been synthesised and their magnetic properties have been studied as a function of particle size and temperature. The particles with sizes of 9 and 14nm exhibited superparamagnetism. The blocking temperature (TB) decreased with decreasing particle size, whereas the anisotropy constant (K) increased. The saturation magnetisation (Ms) decreased with decreasing particle size. These variations are attributed to large surface-to-volume ratios in nanoparticles where the surface moments are predominant