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O: Fachverband Oberflächenphysik
O 10: Oxides I: Growth and Characterization
O 10.11: Vortrag
Montag, 16. März 2020, 13:00–13:15, WIL B321
Large-Scale Quasicrystal Approximants in the SrTiO3/Pt(111) System — •Oliver Krahn1, Sebastian Schenk1, Stefan Förster1, and Wolf Widdra1,2 — 1Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany — 2Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany
The recent discovery of two-dimensional oxide quasicrystals (OQC) draws attention to aperiodic structure formation from perovskite materials on Pt(111) [1,2]. On the atomic level, the OQC generates an aperiodic self-similar tiling consisting of triangles, squares and rhombes with Ti atoms at the vertices and equal edge lengths. Periodically repeated patches of a quasicrystal are known as approximants.
In this talk, we present low-temperature scanning tunneling microscopy and spectroscopy data of the largest unit cell approximant known so far in 2D systems. Its unit cell is commensurate with a superstructure matrix of (
160
918
) with respect to Pt(111) and covers an area of 44.3 Å × 43.2 Å. The cell contains 48 Ti atoms that occupy the vertices of 48 triangles, 18 squares and 6 rhombes. These tiling elements are furthermore decorated with 48 Sr and 120 O atoms assuming a stoichiometry of 1:1:2.5 as determined for a related small unit cell approximant [3]. This adds up to a 2D unit cell containing 216 atoms.
[1] S. Förster et al., Nature 502 (2013)
[2] S. Förster, O. Krahn et al., Phys. Status Solidi B,
doi: 10.1002/pssb.201900624 (2019)
[3] S. Förster et al., Phys. Rev. Lett. 117 (2016)