title: Detection of Fe2+ valence states in Fe doped SrTiO3 epitaxial thin films grown by pulsed laser deposition.
abstract: We present an X-ray absorption spectroscopy study on Fe-doped SrTiO3 thin films grown by pulsed laser deposition. The Fe L2,3 edge spectra are recorded for doping concentrations from 0-5% after several annealing steps at moderate temperatures. The Fe valence state is determined by comparison with an ilmenite reference sample and calculations according to the charge transfer multiplet model. We found clear evidence of Fe(2+) and Fe(3+) oxidation states independently of the doping concentration. The Fe(2+) signal is enhanced at the surface and increases after annealing. The Fe(2+) configuration is in contrast to the mixed Fe(3+)/Fe(4+) valence state in bulk material and must be explained by the specific defect structure of the thin films due to the kinetically limited growth which induces a high concentration of oxygen vacancies.
authors.affiliation: Peter-Grünberg-Institute 7, Forschungszentrum Jülich, 52425 Jülich, Germany. A.Koehl@fz-juelich.de
authors.forename: Annemarie
authors.initials: A
authors.lastname: Koehl
authors.forename: Dariusz
authors.initials: D
authors.lastname: Kajewski
authors.forename: Jerzy
authors.initials: J
authors.lastname: Kubacki
authors.forename: Christian
authors.initials: C
authors.lastname: Lenser
authors.forename: Regina
authors.initials: R
authors.lastname: Dittmann
authors.forename: Paul
authors.initials: P
authors.lastname: Meuffels
authors.forename: Kristof
authors.initials: K
authors.lastname: Szot
authors.forename: Rainer
authors.initials: R
authors.lastname: Waser
authors.forename: Jacek
authors.initials: J
authors.lastname: Szade