SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 92: Oxide and Insulator Surfaces II: Structure, Epitaxy and Growth

O 92.10: Vortrag

Freitag, 31. März 2023, 12:45–13:00, CHE 91

Surface Structures of La_0.8Sr_0.2MnO₃(001): from Commensurate to Quasicrystal Phases — •Erik Rheinfrank¹, Michael Brunthaler¹, Giada Franceschi¹, Peter Matvija², Michael Schmid¹, Ulrike Diebold¹, and Michele Riva¹ — ¹Institute of Applied Physics, TU Wien, Austria — ²Faculty of Mathematics and Physics,Department of Surface and Plasma Science, Charles University, Prague, Czech Republic

Lanthanum-strontium manganite (La_0.8Sr_0.2MnO₃, LSMO) is a perovskite oxide used as a cathode material in solid oxide fuel cells, which convert chemical energy to electrical energy. To gain deeper insights into the reaction mechanisms, it is important to understand the structure of the surface at the atomic scale. To this end, we grow atomically flat single-crystalline LSMO(001) thin films on Nb-doped SrTiO₃ (STO) substrates via pulsed laser deposition (PLD). The as-grown films have a B-site (Mn) rich surface that can be transformed into an A-site (La/Sr) rich structure by Ar⁺ sputtering and subsequent annealing. The B-site rich surface is recovered by depositing Mn from a MnO target. In low-energy electron diffraction (LEED), the Mn-rich surface shows a 4-fold symmetric structure that is best explained by a set of four basis vectors. This is reminiscent of quasicrystals. Scanning tunneling microscopy reveals a non-periodic structure with a Fourier transform consistent with the LEED pattern.