Growth of ultra-thin FeO(100) films on Ag(100): A combined XPS, LEED and CEMS study

• Highly ordered iron oxide ultra-thin film was grown on Ag(100) single crystal.
• The samples were submitted to annealing at various temperatures.
• The changes in the iron oxide phases were checked by LEED, XPS and CEMS.
• The best conditions to prepare the wüstite and magnetite phases were determined .

The production and characterization of ultra-thin iron oxide films grown on an atomically clean Ag(100) surface by molecular beam epitaxy (MBE) is presented. The goal of this work was to prepare ultra-thin FeO(100) with excellent crystallographic quality. The films were prepared with high purity 57Fe and O2 and afterwards analyzed in situ by means of Low Energy Electron Diffraction (LEED), X-Ray Photoelectron Spectroscopy (XPS) and Conversion Electron Mössbauer Spectroscopy (CEMS). During preparation the evaporation rate, the O2 partial pressure, film thickness and annealing procedures were varied. The analysis of the various samples showed that in general a mixture of FeO and Fe3O4 phases is obtained. We determined the best conditions to produce the desired oxide (FeO). Besides the paramagnetic phase, the antiferromagnetic phase of the FeO films was characterized by low temperature Mössbauer spectra.