Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 79: Oxide Surfaces III
O 79.8: Vortrag
Donnerstag, 14. März 2013, 17:45–18:00, H45
Probing Surface and Bulk Phonons in Nickel Oxide — •Srijan Kumar Saha1, Oleg Brovko1, Sebastian Polzin2, Krassimir Kostov2, Florian Schumann2, Wolf Widdra2, and Valeri Stepanyuk1 — 1Max-Planck-Institut fur Mikrostrukturphysik, Weinberg 2, D-06120 Halle/Saale, Germany — 2Martin-Luther-Universität Halle-Wittenberg, Institut für Physik FG Oberflächen- und Grenzflächenphysik, Von-Danckelmann-Platz 3, 06120 Halle/Saale
Using first-principles density-functional theory, we determine the vibrational properties of bulk NiO and its N-layer films; and compare our results with experiments performed by high-resolution electron energy loss spectroscopy (HREELS) on NiO(100) films on Ag(100). Because of the strong Coulomb interaction between the 3d electrons on the transition-metal ion, here we apply the DFT+U approach for this oxide, known as a model system of Mott or charge-transfer insulators. We find that the highest frequency surface optical phonon mode is highly dispersive and exhibits a huge blueshift as a function of number of layers in the film. The underlying physics of our main results will be discussed together with the pictorial representation of the phonon modes.