▎ 摘　　要

Monodisperse iron oxide nanoparticle-reduced graphene oxide composites were prepared by self-assembly in aqueous phase. Pre-synthesized iron oxide nanoparticles were transferred to aqueous phase and then mixed with graphene oxide dispersion. The iron oxide nanoparticles, with a diameter of around 10 nm, were self-assembled on the reduced graphene oxide sheets through electrostatic attraction during the reduction of graphene oxide. The magnetization curves indicated that all samples exhibited ferromagnetic behavior at room temperature with small coercivity. The values of specific saturated magnetization of composites with different densities of iron oxide nanoparticles are 38.3, 19.5, and 7.7 emu/g. Permittivity and permeability of composites exhibit obvious fluctuations, which are ascribed to the multiple magnetic resonances. The multiple resonances involve exchange resonances (the consequence of small size effect, surface effect, and spin wave excitations) and natural resonance.