Magnetite Fe3-deltaO4 : a stoichiometry and structure analysis of MBE grown thin films using NO2 as the oxidising source

Epitaxial single crystalline films of iron oxides have been grown on MgO(100) substrates by means of MBE. Natural Fe or 57Fe was evaporated from alumina crucibles, and oxidised simultaneously with a dosed flux of NO2. The resulting oxide layers have been characterised in situ with RHEED, LEED, XPS, and AES. RHEED intensity oscillations, observed during deposition of the oxides, indicate a layer-by-layer growth for all substrate temperatures between 373 and 673 K. A stoichiometry analysis with CEMS, performed ex situ, shows that it is straightforward to prepare both the stable magnetite Fe3O4 and the metastable maghemite Fe3-dO4 phases. Moreover, also al1 solid solutions in between these two extreme phases, i.e. Fe3-dO4 with