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DS: Fachverband Dünne Schichten

DS 26: Oxides

DS 26.2: Vortrag

Donnerstag, 29. März 2007, 15:15–15:30, H34

Structural Determination of thin Manganese Oxide Films on Ag(001) — •Christian Langheinrich¹, Angelika Chassé¹, Frank Müller², and Stefan Hüfner² — ¹Martin-Luther-Universität Halle-Wittenberg, Institut für Physik, D-06099 Halle/Saale — ²Universität des Saarlandes, Institut für Experimentalphysik, D-66041 Saarbrücken

X-ray photoelectron diffraction (XPD) has been applied to study thin manganese oxide films (∼7 ML) on an Ag(001) surface. Calculations with the multiple scattering cluster model (MSCM) show that the film grows in a high crystalline order. At least the top 5 MLs have to be in such a crystalline order to reproduce the experimental spectra properly.

Furthermore, it is insufficient to analyze the spectra with a simple forward scattering picture, which usually dominates the XPD spectra for high kinetic energies (here ∼850 eV for Mn-2p excitation and ∼970 eV for O-1s excitation). Due to the small next-neighbour distance in a NaCl-like lattice interference effects change the peak form drastically. Thus a combination of forward scattering and interference is necessary to understand these XPD spectra.

In order to find optimized lattice constants, both the lattice constant in the surface and the lattice constant in perpendicular direction have been varied independently. An r-factor analysis of these spectra indicates that the system is close to pure MnO bulk within a small tetrahedral distortion. This is in accordance with low energy electron diffraction (LEED) results.