Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 91: Epitaxy and growth: Oxides and insulators
O 91.6: Vortrag
Donnerstag, 17. März 2011, 18:30–18:45, WIL C307
Phonon dispersion of ultrathin NiO(100) films on Ag(100) — •Sebastian Polzin, Krassimir L. Kostov, and Wolf Widdra — Martin-Luther-Universität Halle-Wittenberg, Institute of Physics, Halle (Saale), Germany
HREELS is employed to characterize the growth and to measure the phonon dispersion of ultrathin NiO films on an Ag(100) surface. The films have been grown by reactive deposition of Ni in an O2 atmosphere. The evolution of the spectra observed for different NiO film thickness between 0.5 and 15 ML will be compared to the dielectric response of an oxide film on a metal substrate. For an 15 ML thick NiO(100) film the phonon dispersion along the Γ-X direction has been determined. The data will be compared to NiO(100) single crystal data measured with HREELS [1] and HAS [2]. Due to the improved resolution two additional phonons have been detected which are visible in the entire surface Brillouin zone. In contrast to earlier work the dispersion of the Lucas mode (S4) and a transverse optical mode (S2) could be measured from the center to the X point at the zone boundary.
[1] Oshima C., Modern Phys. Lett. 5, (1991)
[2] Toennies J. P., et al., J. Electr. Spectr. Rel. Phen. 64/65, (1993)