Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 51: Oxides and insulators: Epitaxy and growth
O 51.1: Vortrag
Mittwoch, 28. März 2012, 16:45–17:00, HE 101
The wurtzite termination of epitaxial CoO(111) films - implications for electronic structure and growth — •Lutz Hammer1, Pascal Ferstl1, Matthias Gubo1, Markus Ostler2, Thomas Seyller2, M. Alexander Schneider1, and Klaus Heinz1 — 1Ls. f. Festkörperphysik, Univ. Erlangen-Nürnberg — 2Ls. f. Techn. Physik, Univ. Erlangen-Nürnberg
Cobalt monoxide films are found to grow on Ir(100) in the polar [111] direction, whereby the outermost subsurface Co layer exhibits a stacking fault altering the local structure from rocksalt- to wurtzite-type [1]. This structural switch renders the surface metallic which is proved both by photoelectron and scanning tunneling spectroscopy (as well as indicated by DFT calculations from the literature [2]). The metallic surface layer allows for the compensation of the film’s dipole moment. In contrast, non-polar CoO(100) films, which can be grown on the same substrate via chemical modification of the interface, remain insulating also at the very surface. The latter films are bulk-like terminated and thus can be grown layer by layer, while this is prohibited by the structural switch in case of the (111) oriented films, which can only be produced via re-crystallisation of initially amorphous films.
[1] W. Meyer et al., PRL 101 (2008) 016103; [2] T. Archer et al., PRB 78 (2008) 014431.