Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 25: Oxide and Insulator Surfaces: Structure and Growth

O 25.2: Poster

Montag, 7. März 2016, 18:15–20:30, Poster E

Oxygen-induced phase switch of sub-monolayer iron oxide on Ir(100) — •Christopher Sobel, Pascal Ferstl, Lutz Hammer, and M.Alexander Schneider — Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7, 91058 Erlangen

By means of STM and LEED we show that two different sub-monolayer iron oxide phases exist on the Ir(100) surface which can be converted into each other by changing the chemical potential of oxygen. In oxygen poor conditions a 3×1-phase of one-dimensional FeO₂ wires forms which covers the whole surface homogeneously. In contrast oxygen rich conditions lead to a condensation into compact islands of quasi-hexagonal FeO(111) with an incommensurate "c(8.8×2)"-structure. The remaining iridium surface is covered by a pure oxygen 2×1-O phase [1]. The energy gain when forming the latter appears to be the driving force for the switch between the extended 3×1 and the compact island iron oxide phase. The behaviour differs qualitatively from other transition metals as for example cobalt, where in oxygen rich conditions the wires change from CoO₂ to CoO₃ stoichiometry. This fact indicates a delicate energy balance between the different phases.
[1] K. Johnson et al., J. Chem. Phys. 112, 10460 (2000)