Regensburg 2016 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 7: Focus Session: Ferroic Domain Walls I

DF 7.3: Vortrag

Dienstag, 8. März 2016, 10:30–10:50, H25

Variable arrangement of domain walls in monoclinic K_0.9Na_0.1NbO₃ epitaxial films on NdScO₃ substrates — •Jutta Schwarzkopf¹, Dorothee Braun¹, Toni Markurt¹, Michael Hanke², and Martin Schmidbauer¹ — ¹Leibniz Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin — ²Paul-Drude Institute, Hausvogteiplatz 5-7, 10117 Berlin

Many macroscopic characteristics of ferroelectric materials are directly related to the physical properties of domains and domain walls. Therefore it is crucial to investigate structure, size and orientation of domains including their domain walls in order to get a fundamental understanding of formation mechanisms and functionality of domain wall, especially with regard to the incorporated lattice strain. In contrast to films with tetragonal, rhombohedral or orthorhombic symmetry the domain walls of monoclinic phases in K_xNa_1−xNbO₃ exhibit variable orientation depending on the components of the spontaneous strain tensor allowing the targeted alignment of the domain walls. In this study K_0.9Na_0.1NbO₃ thin films were grown under anisotropic lattice strain on NdScO₃ (NSO) substrates by metal-organic chemical vapor deposition. Lateral PFM images reveal bundles of ferroelectric domains along the [001]_NSO direction of the substrate. They are superimposed by smaller domains forming regularly ordered herringbone patterns which can be described by alternately arranged monoclinic M_C/a₁a₂ domains. The in-plane angle ±α between the twin domain walls and the [1-10]_NSO direction is determined by the incorporated lattice strain and can intentionally be adjusted between 15^∘ and 45^∘.