Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 89: Oxide and Insulator Surfaces: Structure, Epitaxy and Growth I

O 89.9: Talk

Thursday, March 15, 2018, 12:30–12:45, MA 041

Formation of Transition-Metal-Oxide Chains on Ir(110) — •Tilman Kisslinger¹, Robert Jacob¹, Josef Redinger², M. Alexander Schneider¹, and Lutz Hammer¹ — ¹Lehrstuhl für Festkörperphysik, Universität Erlangen–Nürnberg, D–91058 Erlangen, Germany — ²Institut für Angewandte Physik & CMS, TU Wien

Evaporation of 0.5 ML of the 3d transition metals (TM’s) Co, Ni and Fe at 100 K onto the unreconstructed Ir(110)–(1×1) surface and oxidation at 920 K leads to the formation of large domains of monatomic chains that are separated by two surface lattice parameters in [001] direction as revealed by STM. For all TM = Co, Ni, Fe similar LEED I(V)–spectra are found indicating the same surface structure. This structure was quantitatively determined for the case of TM = Co (R_p = 0.117) revealing CoO₂ stoichiometry. The TM sits at hollow sites of the first Ir layer and is surrounded by four oxygen atoms being threefold coordinated towards two 3d–TM and one Ir atom. All structural parameters are in close agreement to independently conducted DFT calculations.

The structural motif of this system is rather similar to the one found on Ir(100) [1]. However, on Ir(110) the TMO₂ chains do not induce a missing–row reconstruction and thus adsorption sites for possible reaction partners are blocked. This modifies e.g. their reactivity and manifests itself in the higher temperature of 420 K necessary for hydrogen–reduction of the phase on Ir(110), compared to 330 K on Ir(100) [2].

[1]: Ferstl et al., Phys. Rev. Lett. 117, 4 (2016)
[2]: Ferstl et al., Phys. Rev. B 96, 085407 (2017)