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O: Fachverband Oberflächenphysik
O 10: Oxides I: Growth and Characterization
O 10.9: Vortrag
Montag, 16. März 2020, 12:30–12:45, WIL B321
Temperature-dependent SXRD from a two-dimensional oxide quasicrystal — •Sebastian Schenk1, Stefan Förster1, Marc de Boissieu2, and Wolf Widdra1,3 — 1Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany — 2Universite Grenoble Alpes, CNRS, SIMaP, 38402 St Martin d Heres, France — 3Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany
Two-dimensional oxide quasicrystals (OQC) are mono-atomically high ternary oxide layers with 12-fold rotation symmetry forming spontaneous on Pt(111) [1,2]. Here we report on studies of the structural dynamics of the prototypical example of the BaTiO3-derived OQC using surface X-ray diffraction (SXRD) at the SIXS beamline, Soleil. In contrast to periodic systems, temperature-induced changes in the diffraction pattern of OQCs occur not only due to the excitation of phonons (Debye-Waller factor) but also due to additional excitations, called phasons [3]. Both will cause a redistribution of intensity from the Bragg peaks to the diffuse background and will be discussed for temperature-dependent SXRD data in the range from 300 to 1300K. In this way, a separation of frozen-in phason flips and dynamically excited phasons is possible. In addition, changes of the shape of the most intense [1110] diffraction peaks are explained by frozen-in phason flips.
[1] S. Förster et al., Nature 502, 215 (2013)
[2] S. Förster et al., Phys. Status Solidi B, doi: 10.1002/pssb.201900624, (2019)
[3] M. de Boissieu et. al., PRL 95, 105503 (2005)