Regensburg 2016 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 8: Thin Film Characterisation: Structure Analysis and Composition I
DS 8.5: Vortrag
Montag, 7. März 2016, 16:15–16:30, H8
Determing the optical constants of NiO with Resonant X-Ray Reflectivity — •Katrin Fürsich1, Volodymyr B. Zabolotnyy1, Christian Schüßler-Langeheine2, Maurits W. Haverkort3, and Vladimir Hinkov1 — 1University Würzburg, Am Hubland, 97074 Würzburg — 2HZB, Albert-Einstein-Str. 15, 12489 Berlin — 3MPI for CPfS, Nöthnizer Straße 40, 01187 Dresden
NiO has been serving as the model system to study electronic correlations and antiferromagnetism of transition-metal oxides, mostly because of its appealing properties like large bandgap and high Néel temperature. Nevertheless, it is still a challenge to describe NiO theoretically as common methods such as DFT and LDA+U are known to fail. We use Resonant X-Ray Reflectivity (RXR) in combination with cluster calculations to study the optical properties of NiO. RXR is a non-destructive technique with a probing depth >100 nm and sub-nm spatial resolution. Thus RXR provides an excellent opportunity to extract layer-resolved optical constants, which are directly related to physical properties like crystal field effects and spin-orbit interactions. However, because of the screening effects it is hard to determine these parameters theoretically. This results in uncertainties in the calculations. We perform RXR measurements on in situ grown NiO thin films of different thicknesses and on cleaved NiO bulk crystals to overcome these problems and to tune unknown variables in the state of the art cluster calculation. The analysis combines theory and experiment in order to give remarkable insight into the physical properties of correlated electron systems.