Ferroelectric domain structure of anisotropically strained NaNbO3 epitaxial thin films

Schwarzkopf, J.; Schmidbauer, M.; Wördenweber, R.; Duk, A.; Braun, D.

doi:10.1063/1.4876906

Journal Article

FZJ-2014-03512

Ferroelectric domain structure of anisotropically strained NaNbO3 epitaxial thin films

Schwarzkopf, J. (Corresponding Author) ; Braun, D. ; Schmidbauer, M. ; Duk, A. ; Wördenweber, R.FZJ*

2014
American Institute of Physics Melville, NY

Journal of applied physics 115(20), 204105 - (2014) [10.1063/1.4876906]

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Please use a persistent id in citations: http://hdl.handle.net/2128/16802 doi:10.1063/1.4876906

Abstract: NaNbO3 thin films have been grown under anisotropic biaxial strain on several oxide substrates byliquid-delivery spin metalorganic chemical vapor deposition. Compressive lattice strain of differentmagnitude, induced by the deposition of NaNbO3 films with varying film thickness on NdGaO3single crystalline substrates, leads to modifications of film orientation and phase symmetry, whichare similar to the phase transitions in Pb-containing oxides near the morphotropic phase boundary.Piezoresponse force microscopy measurements exhibit large out-of-plane polarization components,but no distinctive domain structure, while C-V measurements indicate relaxor properties in thesefilms. When tensile strain is provoked by the epitaxial growth on DyScO3, TbScO3, and GdScO3single crystalline substrates, NaNbO3 films behave rather like a normal ferroelectric. Theapplication of these rare-earth scandate substrates yields well-ordered ferroelectric stripe domains ofthe type a1/a2 with coherent domain walls aligned along the [001] substrate direction as long as thefilms are fully strained. With increasing plastic lattice relaxation, initially, a 2D domain pattern withstill exclusively in-plane electric polarization, and finally, domains with in-plane and out-of-planepolar components evolve.

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