Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 89: Oxides and Insulator Surfaces II
O 89.6: Vortrag
Donnerstag, 10. März 2016, 16:30–16:45, H4
Another 2-dimensional oxide quasicrystal: Strontium titanate on Pt(111) — •Sebastian Schenk1, René Hammer1, Florian Schumann1, Stefan Förster1, Klaus Meinel1, and Wolf Widdra1,2 — 1Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany — 2Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany
Recently the formation of a BaTiO3-derived 2-dimensional oxide quasicrystal (OQC) with 12-fold diffraction symmetry has been discovered on Pt(111) substrates [1]. Following an analogous preparation procedure, we show that SrTiO3 on Pt(111) develops an OQC as well. First, a closed SrTiO3 film on Pt(111) has been prepared using MBE. The stoichiometry and structure of the film has been analyzed by means of AES and SPA-LEED. Annealing the film in an O2 atmosphere yields the formation of 3-dimensional SrTiO3 islands with bare Pt(111) in between. Annealing in UHV causes a rewetting on the Pt(111) via surface diffusion of SrTiO3 from the islands. SPA-LEED and STM reveal that at temperatures around 700∘C an OQC is formed in the rewetting layer. The SrTiO3 derived OQC is composed by quadratic, triangular, and rhombic elements of equal side length of about 0.6 nm. They form an aperiodic structure, which displays a well-ordered 12-fold diffraction pattern. Our results suggest that OQC formation is a general process of oxide perovskites on suitable substrates.
[1] S. Förster, K. Meinel, R. Hammer, M. Trautmann, and W. Widdra, Nature 502 (2013) 215.