Epitaxial MgFe2O4 thin films were synthesized by oxide molecular beam epitaxy at 300 degrees C. Reflection high energy electron diffraction and transmission electron microscopy showed that the films were epitaxial with a (001) orientation. Magneto-optic Kerr effect and superconducting quantum interference device magnetization measurements revealed that films were ferrimagnetic with a saturation ellipticity of 5 mdeg, and saturation magnetization of 120 emu/cm(3), respectively. The ferrimagnetism was attributed to the formation of a partially inverted spinel structure with a cation site distribution of [Mg0.22+Fe0.83+][Mg0.82+Fe1.23+]O-4. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3054339]