Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)

O 58.13: Poster

Mittwoch, 13. März 2013, 18:15–21:45, Poster B1

Two-photon photoemission of thin CoO-Films on Ir(100)-(1x1) — •Sebastian Otto and Thomas Fauster — Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany

Two-photon photoelectron spectroscopy is used to study unoccupied states on thin CoO films grown epitaxially on Ir(100)-(1x1). Unoccupied states were found on various reconstructions of one Co-monolayer thick films with different oxygen amounts [1] and CoO(111) films [2] with thickness of up to ten bilayers. Ultrathin CoO films with a Co amount of about one monolayer show an increasing energy of the unoccupied state from 2.36 to 4.03 eV and an increase of the work function from 5.18 to 6.12 eV with increasing oxide content. For low coverages the observed states are in good agreement with scanning tunneling spectroscopy measurements [3]. On thicker CoO(111) films an increase of the energy from 3.36 to 3.62 eV with film thickness is found, while the work function decreases from 6.01 to 5.69 eV. A comparison with calculations for bulk CoO [4] suggests that the observed states correspond to unoccupied Co 3d orbitals.
[1] M. Gubo, C. Ebensperger, W. Meyer, L. Hammer and K. Heinz. Phys. Rev. B 83 (2011) 075435.
[2] K. Biedermann, M. Gubo, L. Hammer and K. Heinz. J. Phys.: Condens. Matter 21 (2009) 185003.
[3] C. Tröppner. Dissertation, Universität Erlangen-Nürnberg (2011).
[4] V. I. Anisimov, F. Aryasetiawan and A. I. Lichtenstein. J. Phys.: Condens. Matter 9 (1997) 767.