Berlin 2015 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 5: Poster Session on Ferroic Domain Walls - Multiferroics (DF with KR/MA/TT)

DF 5.1: Poster

Montag, 16. März 2015, 19:00–21:00, Poster C

Superdomains in K_0.9Na_0.1NbO₃ thin films on NdScO₃ substrates — •Jutta Schwarzkopf¹, Martin Schmidbauer¹, Dorothee Braun¹, Albert Kwasniewski¹, Jan Sellmann¹, and Michael Hanke² — ¹Leibniz Institute for Crystal Growth, Berlin, Germany — ²Paul- Drude-Institut für Festkörperelektronik, Berlin, Germany

Incorporation of lattice strain in thin films gives rise to the creation of controlled arrays of domains and can lead to very complex domain structures. Understanding of strain induced domain formation will open the possibility to selectively influence film properties. Due to its orthorhombic symmetry (K,Na)NbO₃ films offer a large variety of ferroelectric and ferroelastic domain types. In this study K_0.9Na_0.1NbO₃ thin films were grown under slight compressive lattice strain on NdScO₃ substrates by MOCVD. Lateral PFM images of the (100) oriented films reveal bundles of ferroelectric domains along the [001] substrate direction and a width of 100-200 nm which are superimposed by ferroelastic domains forming regularly arranged herringbone patterns with a periodicity of 30 nm. The domain walls within the domain bundles are tilted alternatingly by +15^∘ and -15^∘ with respect to the [110] orientation of the substrate. Grazing incidence x-ray diffraction experiments have shown that adjacent superdomain bands exhibit an in-plane monoclinic lattice distortion of 0.12^∘. We conclude that the hierarchical structure leads to a domain formation on two scales, which effectively release the misfit strain in the film induced by the substrate.