Berlin 2015 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 9: Focused Session on Ferroic Domain Walls III (DF with MA)
DF 9.1: Vortrag
Dienstag, 17. März 2015, 14:00–14:20, EB 107
STM imaging of ferroelectric domains of strained BaTiO3 films at the thickness limit — •Maik Christl1, Klaus Meinel1, Stefan Förster1,2, and Wolf Widdra1,3 — 1Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany — 2Department of Physics, University of Zurich, Zurich, Switzerland — 3Max Planck Institute of Microstructure Physics, Halle, Germany
Ultrathin ferroelectric films are of increasing interest due to novel oxide based applications. In particular, the domain structure as well as the critical thickness are essential key aspects for ferroelectricity in thin films [1].
In this work, we report on in-situ STM and STS studies to image ferroelectric out-of-plane and in-plane nanodomain structures. BaTiO3(100) ultrathin films have been grown pseudomorphically on Pt(100) and Au(100), which corresponds to 2% lateral compression and 2% expansion, respectively [2]. Films with a thickness of 2 unit cells (uc) show already ferroelectricity at room temperature as verified by reversible domain writing and reading using STM. On Pt(100), an irregular c+/c− nanodomain configuration is visible in dI/vV maps that are taken at domain sensitive voltages. With film thickness, the domain width increases from 2 nm for 2 uc to 6 nm for 25 uc. In contrast, for expanded BaTiO3 films on Au(100) a regular structure with domain walls proceeding along [100] directions is observed which evidences an in-plane domain arrangement.
[1] Y. Wang et al., Materials 7, 103390 2014
[2] S. Förster et al., J. Chem. Phys. 135, 104701 2011