Regensburg 2002 – wissenschaftliches Programm

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SYCO: Cluster auf Oberflächen

SYCO 4: Posters (will be on the whole day)

SYCO 4.1: Poster

Donnerstag, 14. März 2002, 18:45–19:30, H 36 Foyer

Structure of Nickel clusters on Al2O3(0001) studied by dynamic mode force microscopy — •Clemens Barth1, Sebastian Gritschneder1, Mohsen Mozaffari-Afshar2, Thomas Risse2, Hans-Joachim Freund2, and Michael Reichling11Department Chemie, Universität München, Butenandtstraße 5-13. 81377 München, Deutschland — 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Deutschland

Prerequisite to an understanding of the magnetic properties of magnetic materials dispersed on dielectric substrates is a sound knowledge of their structural properties. Scanning force microscopy (SFM) is the only technique that allows reliable imaging of nanometer sized metallic surface structures on an insulator. We investigated Ni clusters thermally evaporated on a well prepared (0001) surface of an Al2O3 crystal. SFM measurements were performed on the as-prepared surface and after annealing the film at 550 K for 20 hours. We find that the as-prepared particles with a mean height of 0.7 nm re-shape during annealing and form smoother clusters with 1 nm height. Most interesting is, the peculiar shape of the annealed clusters exhibiting straight boundary lines with an almost hexagonal footprint. We interpret the observed changes as due to the formation of small Nickel crystallites with sides consisting of low index surfaces and a (111) orientation with respect to the surface normal.

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