Abstract
(111)- and (100)-oriented Fe3O4/MgO superlattice films were prepared on α-Al2O3 and MgO single crystalline substrates, respectively. The artificial modulation periods estimated from the satellite positions of the X-ray diffraction peaks were in good agreement with the designed ones. Magnetization curves at room-temperature could be decomposed into an easily saturated component and a linear component proportional to the applied magnetic field. With decreasing temperature the magnetization increased rapidly below 20K, just like superparamagnetizm. The saturation magnetization at 5K was nearly consistent with that of the Fe, 04 bulk. The Mossbauer spectrum at room-temperature consisted of a pair of magnetic components assigned to iron ions located on the Fe3O4 lattices. But the magnetic hyperfine fields of both components were a little suppressed, compared with those of the Fe3O4 bulk. Magnetic spins at about 20A-thick interface regions of each Fe3O4 layer seem to be thermally fluctuated at room-temperature.
