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O: Oberflächenphysik

O 4: Epitaxie und Wachstum I

O 4.1: Vortrag

Freitag, 4. März 2005, 10:45–11:00, TU EB202

Unidirectional patterning of transition-metal films on Ir(100) — •Chiara Giovanardi, Andreas Klein, Andreas Schmidt, Lutz Hammer, and Klaus Heinz — Lehrstuhl für Festkörperphysik, Universität Erlangen Nürnberg, Staudtstr. 7, D-91058 Erlangen

We report and compare the unidirectional patterning of Fe, Ni and Co ultrathin films deposited on the hydrogen-stabilized substrate Ir(100)-(5×1)-H. This template develops by exposure of the Ir(100)-(5×1)-hex phase to hydrogen and consists of long, regularly spaced and defect-free Ir monoatomic wires residing on the (1×1) structured Ir substrate. The space between the wires can be filled by deposition of the transition metals (TM) Fe, Co and Ni. We show by STM that this filling process is rather different for the three metals but eventually results, at 0.8 ML coverage, in lateral superlattices {TM₄Ir}. The crystallographic structure of the three compounds was determined by quantitative LEED, which also reveals that there is no intermixing of TM atoms with the Ir wires. By further TM deposition, the superlattice is covered by pure TM in a layer-by-layer growth mode. In the second and third layer, atoms deviate from the ideal quadratic arrangement as induced by the 1-dim. corrugated structure of the {TM₄Ir} interface. The vertical buckling of the interface is imprinted in the TM film, with a maximum amplitude of e.g. 0.11 Å in the third Ni layer. Laterally, the atomic rows above the Ir chains of the interface have a larger separation and, under special conditions, can be decorated by further TM adatoms leading to well separated chain structures on top of the film.