Berlin 2015 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 7: Focused Session on Ferroic Domain Walls II (DF with MA)
DF 7.3: Vortrag
Dienstag, 17. März 2015, 10:20–10:40, EB 107
Ferroelectric 180∘ domain wall motion controlled by biaxial strain — •Robert Roth1, Er-Jia Guo1,2, Andreas Herklotz1,2, Dietrich Hesse3, and Kathrin Dörr1,2 — 1MLU Halle-Wittenberg, Institute for Physics, 06099 Halle, Germany — 2Institute for Metallic Materials, IFW Dresden, Postfach 270116, 01171 Dresden, Germany — 3Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
Switching polarization in a ferroelectric proceeds by nucleating reversed domains which subsequently expand. Therefore, wall velocity (v) limits the speed of switching. In thin films, measured values of v are many orders below sound velocity [1], whereas bulk crystals showed larger v. Why are domain walls in films so slow? New insights can be derived from local studies of domain wall velocity by piezoresponse force microscopy in in-situ controlled elastic strain states of the sample. In c-oriented epitaxial PbZr0.2Ti0.8O3 films on piezoelectric substrates, the velocity of non-ferroelastic 180∘ walls has been investigated employing the approach of Tybell et al. [2]. Remanent circular domains showed strong strain dependences of both, domain relaxation / shrinking in zero electric field and field-driven velocity. We discuss results in the light of known physical mechanisms, identify a strain-induced change of the driving field arising from built-in Schottky junctions at electrodes and suggest a new mechanism of strain-induced charging of tilted domain walls (wall sections).
[1] A. Grigoriev et al., Phys. Rev. Lett. 96, 187601 (2006)
[2] T. Tybell et al., Phys. Rev. Lett. 89, 097601 (2002)