Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 27: Nanostructures: Low Dimensions
O 27.3: Vortrag
Dienstag, 17. März 2015, 14:30–14:45, MA 005
Reversible and self-organized formation of periodic 1D cobalt nanostructures — •Pascal Ferstl1, Marina Schuler1, Lutz Hammer1, Klaus Heinz1, M.Alexander Schneider1, Florian Mittendorfer2, Josef Redinger2, M. Alif Arman3, Edvin Lundgren3, and Jan Knudsen3,4 — 1Lst. für Festkörperphysik, FAU Erlangen-Nürnberg — 2Inst. für Angewandte Physik and Center for Computational Materials Science, TU Wien — 3Division of Synchrotron Radiation Research, Lund University — 4The MAX IV Laboratory
By alternate oxidation and reduction of 1/3 ML of cobalt deposited on the unreconstructed Ir(100) surface two different quasi one-dimensional nanostructures can be formed and reversibly transformed into each other: An oxygen-rich and an oxygen-free phase, which both show a well ordered single domain 3×1 periodicity.
In this study we present the atomic structure of these two phases revealed by means of quantitative LEED, STM, HRXPS and DFT calculations. The oxygen-free 3×1 phase is an ordered Ir2Co surface alloy, where every third iridium row of the outermost layer is substituted by a cobalt row. Adsorption of oxygen transforms the latter into a metal-oxide hybrid system with CoO2 stoichiometry. In this structure the Co rows are drastically lifted above the first Ir layer so that there are no more direct Co-Ir bonds. The clean Co-Ir alloy phase can be restored again by reducing the CoO2 phase in hydrogen at only 80∘C.