Magnetic iron oxide films were grown by atomic layer deposition. The films were grown from ferrocene and ozone precursors on planar and 3D SiO2/Si substrates. Some substrates were pre-covered with self-assembled SnO2 nanoparticles, prepared by hydrolysis of tin alkoxide with large excess of water. All samples demonstrated hysteresis in magnetization-field curves, defined and characterized on both planar and 3D substrates. The films on SnO2 possessed slightly higher coercivity and markedly higher saturation magnetization compared to the films on SiO2/Si. Both Fe2O3 and Fe3O4 were recognized in the as-deposited films without reducing Fe2O3 in H-2. The application of SnO2 nanoparticles influenced the composition, also promoting growth and magnetization. The samples deposited at 350 degrees C on 3D substrates with nanoparticles exhibited saturation magnetization of 0.0075 emu/g, whereas in the samples without nanoparticles the magnetization remained at 0.0025 emu/g. The highest coercivity of 425 Oe was measured at room temperature in the film deposited at 400 degrees C on planar substrate with SnO2 nanoparticles. (C) 2012 Elsevier B.V. All rights reserved.