Photo-induced electric polarizability of Fe^sub 3^O^sub 4^ nanoparticles in weak optical fields

Using a developed co-precipitation method, we synthesized spherical Fe^sub 3^O^sub 4^ nanoparticles with a wide nonlinear absorption band of visible radiation. Optical properties of the synthesized nanoparticles dispersed in an optically transparent copolymer of methyl methacrylate with styrene were studied by optical spectroscopy and z-scan techniques. We found that the electric polarizability of Fe^sub 3^O^sub 4^ nanoparticles is altered by low-intensity visible radiation (I