Synthesis and property of core-shell Ag@[Fe.sub.3][O.sub.4] nanoparticles

Ag nanoparticles with [Fe.sub.3][O.sub.4] shells have been synthesized by the polyol method. The Ag@[Fe.sub.3][O.sub.4] core-shell nanoparticles exhibited a superparamagnetic behavior at the temperature higher than the blocking temperature (100 K) and showed shifted loops under a field cooling process. The enhanced magnetic anisotropy was observed and was ascribed to the surface effect. Index Terms--Core-shell structure, exchange bias, [Fe.sub.3][O.sub.4] nanoparticles, superparamagnetic.