Dresden 2009 – scientific programme

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DS: Fachverband Dünne Schichten

DS 26: Poster II

DS 26.46: Poster

Wednesday, March 25, 2009, 09:30–12:30, P5

Surface Electronic Structure Of Perovskite Oxides — •Christoph Raisch¹, Robert Werner², Reinhold Kleiner², Dieter Koelle², and Thomas Chassé¹ — ¹Universität Tübingen, Institut Für Physikalische Chemie, Auf der Morgenstelle 8 — ²Universität Tübingen, Experimentalphysik II, Auf der Morgenstelle 14, 72076 Tübingen

We report on x-ray absorption (XAS) and photoemission spectroscopy (PES) on La_0.7Ce_0.3MnO₃ (LCeMO) and La_0.7Ca_0.3MnO₃ (LCMO) films with varying oxygen content grown by PLD on SrTiO₃ substrates. Our previous work¹ focused on bulk properties, but also showed how important the near-surface region is for the complete understanding of the electronic structure of the films. The samples have thus been further examined by PES and photoelectron diffraction (PED). To investigate effects of varying oxygen contents, the samples were heated in vacuum or in oxygen to adjust the amount of manganese valences, which were determined by PES. The experiments are supported by multiple scattering cluster calculations and atomic multiplet calculations. The simulations reveal the termination of the films, which is important considering all kinds of charge/spin injection experiments. Finally, the electronic structure of the surface also explains the behaviour of the XMCD signal, showing antiferromagnetic ordering at the surface and ferromagnetic coupling in bulk.
¹Werner,R., Raisch,C., Leca,V. et al., ’Transport, magnetic, and structural properties of LCeMO thin films: Evidence for hole-doping’ submitted to Phys. Rev. B.