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O: Oberflächenphysik

O 14: Poster session I (Adsorption, Epitaxy and growth, Phase transitions, Surface reactions, Organic films, Electronic structure, Methods) (sponsored by Omicron Nanotechnology GmbH)

O 14.31: Poster

Montag, 27. März 2006, 18:00–21:00, P2

Structure and Composition of Ultra-thin Fe Layers on Pt(111) — •R. Chopra, T.Y. Lee, A. Enders, K. Kuhnke, U. Starke, and K. Kern — Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany

The growth of Fe on vicinal Pt surfaces provides access to magnetic nanostructures with interesting properties. In order to understand the structural properties of the Fe-Pt interface and the alloying process during annealing, ultra-thin epitaxial Fe films were studied on flat Pt(111). Low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES) were used to characterize the film properties after deposition and upon annealing. Fe films between 0.5 ML and 3 ML display a non-pseudomorphic arrangement, although with limited long-range order immediately after deposition at 90 K or room temperature. Yet, a tendency towards a specific epitaxial relationship between the bcc-film and the fcc-substrate is observed in LEED that develops into very well ordered incommensurate superstructures corresponding to a Kurdjumov-Sachs orientation at about 500 to 600 K. At these temperatures, the initial Fe richness after deposition is considerably reduced according to AES. Further annealing to about 700 to 800 K leads to a further reduction of the Fe/Pt composition ratio accompanied by a (2×2) LEED pattern. Detailed inspection of the LEED spots and their intensity reveals the presence of a (2×1) superstructure in three domains. This phase is attributed to a Pt-Fe surface alloy.