Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 51: Oxides and insulators: Epitaxy and growth

O 51.2: Vortrag

Mittwoch, 28. März 2012, 17:00–17:15, HE 101

Tuning the growth orientation of epitaxial films by the interface chemistry — •Florian Mittendorfer¹, Josef Redinger¹, Matthias Gubo², Christina Ebensperger², Wolfgang Meyer², Lutz Hammer², and Klaus Heinz² — ¹TU Vienna, Austria — ²Univ. Erlangen-Nürnberg, Germany

The support of epitaxial films frequently determines their crystallographic orientation, which is of crucial importance for their electronic and catalytic properties. We have investigated the growth of CoO films on Ir(100) with density functional theory (DFT) calculations, using the Vienna Ab-initio Simulations Package (VASP), in combination with scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) experiments.

The measurements show that the oxide film grows in the (111) orientation on the bare substrate, but the orientation switches to (100) by introducing a single layer of metallic Co between the oxide and substrate. On the basis of the DFT calculations, we find that these different growth modes are triggered by an oxide precursor structure, which is only stable on the Co/Ir(100) surface. The calculations demonstrate that the stabilization of the precursor is not driven by the surface stress, but rather by the chemical modification of the interface. Therefore, this approach offers a new way to change the film orientation without changing the substrate.