Materials Science and Engineering B 109, 207 (2004)
EMRS 2003, Symposium I, Functional Metal Oxides – Semiconductor Structures

S. A. Krasnikov, A. S. Vinogradov, K. -H. Hallmeier, R. Höhne, M. Ziese, P. Esquinazi, T. Chassé and R. Szargan

Abstract

Fe₃O₄ films of different thickness were epitaxially grown on single crystal MgO and MgAl₂O₄ substrates and studied by X-ray absorption, X-ray photoemission spectroscopy and X-ray fluorescence (XF). All samples were prepared by pulsed laser deposition (PLD) and some of them were covered by in situ prepared thin BaTiO₃ protecting layer. The photoemission (VG ESCALAB 220i-XL) and absorption (total electron yield mode) measurements on epitaxial Fe₃O₄ films demonstrate the important role of the protecting layer to prevent the further oxidation of Fe₃O₄ to Fe₂O₃ in the case of thin films (2.5 nm range). The resonant XF (X-ray monochromator XES 300 using synchrotron radiation at the U41-PGM beam-line at BESSY II) measurements at excitation energy 710 eV (Fe L₃ absorption edge) demonstrate the effect of the Fe 3d–O 2p hybridization in the iron oxide layers. Information about local partial densities of states was obtained for the oxidized Fe₃O₄ film from a comparative analysis of the Fe L and O K XF and the valence-band photoelectron spectra.