SKM 2021 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 21: Focus Session: Highlights of Materials Science and Applied Physics II (joint session DS/HL)

HL 21.2: Talk

Friday, October 1, 2021, 10:15–10:30, H1

Structure solution of a large unit cell approximant derived from SrTiO₃ on Pt(111) — •Stefan Förster¹, Sebastian Schenk¹, Oliver Krahn¹, Holger L. Meyerheim², Marc DeBoissieu³, and Wolf Widdra¹ — ¹Martin-Luther-Universität Halle-Wittenberg, Halle, Germany — ²Max-Planck-Institut für Mikrostrukturphysik, Halle, Germany — ³Universite Grenoble Alps, CNRS, SIMaP, Saint-Martin d’Hères, France

The discovery of two-dimensional oxide quasicrystals (OQC) has caused a great amount of interest in aperiodic structure formation from perovskite materials on metal surfaces [1]. In recent years, a plethora of surface science techniques has been applied to OQCs to get an understanding of this peculiar materials system on the fundamental level [2]. In this contribution, we present low-temperature scanning tunneling microscopy (STM) and surface x-ray diffraction (SXRD) investigation of the largest unit cell approximant known so far in 2D systems. Its unit cell covers an area of approximately 44 Å × 44 Å and has p2gg symmetry. STM measurements show 48 atoms in the unit cell forming the vertices of 48 triangles, 18 squares and 6 rhombuses. The structure has been solved utilizing over 300 independent reflections measured by SXRD with an R-factor better than 0.20. From this analysis a profound understanding of the decoration of all tiles with Sr, Ti, and O ions is derived, which solves the structure of the parent OQC.
[1] S. Förster et. al., Nature 502, 215 (2013).
[2] S. Förster et al., Phys. Status Solidi B 257, 1900624 (2020).