The surface insulator-metallic phase transition of epitaxial magnetite thin film observed by low-energy ion scattering

The (1 1 1) surface of the magnetite thin film has been investigated by low-energy ion scattering (LEIS) in the small-angle geometry and in the temperature range 85-300 K. The thin film has been grown by molecular beam epitaxy (MBE) and characterized by low-energy electron diffraction (LEED), scanning tunneling microscopy (STM) and conversion electron Mossbauer spectroscopy (CEMS). The temperature dependence of the scattered ion yield, R+(T), obtained by LEIS technique has shown anomaly around 120 K attributed to the insulator-metallic phase transition of this material. The character of the R+(T) curve has been found to depend on the velocity of incoming ions. The resonant and Auger neutralization, which depends on the density of state and on the degree of electron localization, can be responsible for the behavior of the R+(T) curve, especially in the phase transition region. (C) 2000 Elsevier Science B.V. All rights reserved.