A comparable study of the microstructure and magnetic properties was performed for magnetite films deposited on (100)-oriented MgO and SrTiO3 (STO) substrates. The growth of strained high quality Fe3O4 films was confirmed by x-ray diffraction analysis and Raman spectroscopy measurements. The surface morphology and magnetic properties of the two films were found to be obviously different. Moreover, a stripelike magnetic domain structure was observed in the film on STO. Substrate-induced strain is believed to be responsible for these observations, which significantly affects the magnetic anisotropy and the magnetic coupling at the antiphase boundaries in the films. © 2008 American Institute of Physics.