Magnetic phase transitions at interfaces studied by resonant magnetic soft X-ray scattering

Properties of magnetic thin films are strongly influenced by the near-interface regions, where modifications of bulk magnetic order and roughness occur. Using resonant magnetic soft X-ray scattering at the Eu-M5 resonance, we studied the temperature-dependent magnetization of the individual layers in monocrystalline films of the magnetic semiconductor EuSe with thicknesses of 20 and 40 monolayers. These films exhibit AFM, ferri-(FiM) and FM phases depending on temperature and applied magnetic field. Due to the high magnetic sensitivity at resonance, very intense AFM and FiM Bragg peaks could be recorded that are characterized by pronounced Laue oscillations over a large range of momentum transfer. These permit a detailed characterization of temperature-dependent interface-induced disorder for different types of magnetic structures (AFM, FiM) in a single material. Preliminary analyses point to a much stronger influence of the interface on the FiM structure than on AFM order