Dresden 2014 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 23: Invited Talk - Stefan Förster (Joint Session with DF, O, KR, MM)
DS 23.1: Hauptvortrag
Mittwoch, 2. April 2014, 10:30–11:15, GER 37
Two-dimensional Oxide Quasicrystals: A new class of materials? — •Stefan Förster1, Klaus Meinel1, Rene Hammer1, Martin Trautmann1, and Wolf Widdra1,2 — 1Martin-Luther-Universität Halle-Wittenberg, Halle, Germany — 2Max-Planck-Institut für Mikrostrukturphysik, Halle, Germany
Two-dimensional materials - like graphene, hexagonal boron nitride, or topological insulators - have recently pioneered a new field of materials science. Their peculiar properties are often related to their specific two-dimensional periodic structure.
Here we report the first observation of a two-dimensional oxide quasicrystal (QC), a new member in the family of 2D materials [1]. The QC is derived from BaTiO3 thin films on a hexagonal Pt(111) substrate. Low-energy electron diffraction (LEED) reveals a twelve-fold rotational symmetry. Scanning tunneling microscopy (STM) at room temperature as well as at low temperatures (80 K) allow to resolve the atomic structure. The aperiodic structure is formed by primitive atomic arrangements in squares, triangles, and rhombi with a universal edge length of 0.69 nm. In addition to this dodecagonal atomic arrangement, building blocks of squares, triangles,and rhombi are also found on (2+√3) and (2+√3)2 larger scales indicating the characteristic self-similarity of an ordered QC. The observed interface-driven formation of a 2D QC from a perovskite oxide in contact with a hexagonal substrate is expected to be a general phenomenon.
[1] S. Förster, K. Meinel, R. Hammer, M. Trautmann, and W. Widdra, Nature 502, 215 (2013).