Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 60: Poster Session III (Methods: Atomic and electronic structure; Methods: electronic structure theory; Methods: Molecular simulations and statistical mechanics; Methods: Sanning probe techniques; Methods: other (experimental); Methods: other (theory) )

O 60.13: Poster

Wednesday, March 24, 2010, 17:45–20:30, Poster B2

Growth of Co-Salen on NiO(001): An atomic force microscopy study in ultrahigh vacuum — •Johannes Hattendorff, Alexander Schwarz, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Jungiusstr. 11, 20355 Hamburg, Germany

Co-Salen is a paramagnetic metal-organic Schiff-base-complex with a central cobalt atom that carries spin. In previous studies the adsorption and growth of Co-Salen was investigated with atomic force microscopy (AFM) on bulk NaCl(001) [1]. The latter investigation revealed that at room temperature the physisorbed molecules are very mobile on NaCl(001) and exhibit a three-dimensional Vollmer-Weber type of growth. Step decoration and two different well ordered crystalline morphologies with bulk-like structures could be identified.

Here we deposit Co-Salen on NiO(001) which is an insulator like NaCl but with a smaller band gap (3.8 eV instead of 9 eV). First results obtained with AFM for sub-monolayer coverage show a step-flow growth and the formation of islands on terraces. At higher coverage the growth appears to be layer-wise. These observations indicate that the molecule-surface interaction on the transition-metal oxide NiO is very different compared to the alkali-halide NaCl. Note that although both surfaces are ionic with rock salt structure bonds in NiO exhibit a significant covalent character and the lattice constant is much smaller (417 pm instead of 564 pm). Both properties might alter the adsorption geometry and interaction strength drastically.

[1] S. Fremy et al., Nanotechnology 20, 405608 (2009).