Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 88: Metallic Nanostructures II (on Semiconductors)
O 88.5: Vortrag
Freitag, 29. Februar 2008, 10:30–10:45, MA 005
Aluminum oxide on Ni3Al(111). A Template for Ordered Fe and Co Cluster Growth — •Andreas Buchsbaum1, Micheal Schmid1, Georg Kresse2, and Peter Varga1 — 1Inst. f. Allg. Physik, TU Wien, Austria — 2Faculty of Physics, CMS, University of Vienna, Austria
The structure of the aluminum oxide on Ni3Al(111), which has been solved recently, exhibits holes at the corner of the (√67 × √67) R12.2∘ unit cell, reaching down to the metal substrate [1]. These holes are large enough to trap atoms of any kind of metal. Therefore, the ultrathin oxide film, forming a nanomesh, should be a perfect template for growing highly regular arranged metal clusters. Several metals have been deposited on the aluminum oxide and the clusters grown have been studied by scanning tunneling microscopy. The unmodified oxide, however, is not a good template for most metals. While Pd atoms nucleate in the corner holes and, hence, show a perfect hexagonal arrangement, Fe and Co clusters grow on other local defects, indicating a barrier to jump into the hole. By predeposition of a Pd seed layer, however, we can create a metallic nucleation site on each corner hole and Fe as well as Co clusters form a well-ordered hexagonal arrangement, making the oxide to a versatile template for growing highly regular arranged metal clusters [1]. We have also studied the morphology of the clusters and applied different methods to determine the orientation of the clusters. We have found different types of clusters, where only few of them show flat close-packed facets on top.
[1] M.Schmid et al., Phys. Rev. Lett. 99, 196104 (2007).