Solvothermal synthesis and characterization of functionalized graphene sheets (FGSs)/magnetite hybrids

► Functionalized graphene sheets/Fe3O4 hybrids were synthesized through solvothermal method. ► The denseness, size and crystallinity of magnetite formed on FGSs can be altered. ► The as-prepared hybrids exhibited high resistivity and saturation magnetization. ► The magnetic loss was caused mainly by ferromagnetic natural resonance.