Dresden 2017 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 11: Ferroics - Domains, Domain Walls and Skyrmions II

DF 11.5: Vortrag

Mittwoch, 22. März 2017, 11:00–11:15, WIL B321

Monoclinic superdomains in ferroelectric K_0.7Na_0.3NbO₃ thin films on TbScO₃ — •Leonard von Helden¹, Martin Schmidbauer¹, Dorothee Braun¹, Christoph Feldt¹, Michael Hanke², and Jutta Schwarzkopf¹ — ¹Leibniz Institut für Kristallzüchtung, Max-Born-Str. 2, 12389 Berlin — ²Paul-Drude-Institut für Festkörperelektronik, Hausvogteipl. 5-7, 10117 Berlin

K_xNa_1−xNbO₃ is a promising material for lead free ferro- and piezoelectric applications. Enhanced piezoelectric properties can be achieved by incorporating anisotropic lattice strain in epitaxial thin films. Monoclinic domains, which are favorable as they enable a continuous rotation of the polarization vector within the monoclinic mirror plane, were shown to be stabilized in K_0.7Na_0.3NbO₃ thin films grown by MOCVD on TbScO₃ substrates.^[1]
In this study we present the coexistence of four variants of superdomains in (001)_pc oriented K_0.7Na_0.3NbO₃ films on TbScO₃ with a film thickness of 30 nm. Below this thickness, only two types of superdomains occur. Each superdomain consists of periodically ordered stripe domains which are characterized by their vertical and lateral response in piezoresponse force micrographs (PFM) indicating different local piezoelectric coefficients. The domain structure can tentatively be described by monoclinically distorted unit cells, whose in-plane orientation is rotated by 90^∘ between the stripe domains. A domain model is presented based on X-Ray diffraction experiments using a nano-focused beam.
^[1] J. Schwarzkopf et al., J. Appl. Crys., 49, 375-384, (2016)