X-ray photoemission spectroscopy of $Sr2FeMoO6$ film stoichiometry and valence state

The authors have used a combination of monochromatized x-ray photoemission spectroscopy and Rutherford backscattering spectrometry to develop a protocol for determining bulk film stoichiometry and charge state of $Sr2FeMoO6$ epitaxial films These studies identify an optimum ion sputtering process for removing surface contaminants while avoiding preferential sputtering of film constituents or alteration of their characteristic valence states. For $Sr2FeMoO6$⁠, low energy (500 eV), glancing incidence $Ar+$ sputtering for short (tens of seconds) periods is successful in achieving stoichiometric compositions and characteristic charge states of the film constituents. The evolution of composition and valence state with sputtering provides a guide to measure stoichiometry and charge state of complex oxide thin films in general.