In-plane quasi-single-domain BaTiO<sub>3</sub> via interfacial symmetry engineering.

Lee, J W; Eom, K; Paudel, T R; Wang, B; Lu, H; Huyan, H X; Lindemann, S; Ryu, S et al. · Nat Commun · 2021

basic_science · Level V

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Abstract

The control of the in-plane domain evolution in ferroelectric thin films is not only critical to understanding ferroelectric phenomena but also to enabling functional device fabrication. However, in-plane polarized ferroelectric thin films typically exhibit complicated multi-domain states, not desirable for optoelectronic device performance. Here we report a strategy combining interfacial symmetry engineering and anisotropic strain to design single-domain, in-plane polarized ferroelectric BaTiO<sub>3</sub> thin films. Theoretical calculations predict the key role of the BaTiO<sub>3</sub>/PrScO<sub>3</sub> [Formula: see text] substrate interfacial environment, where anisotropic strain, monoclinic distortions, and interfacial electrostatic potential stabilize a single-variant spontaneous polarization. A combination of scanning transmission electron microscopy, piezoresponse force microscopy, ferroelectric hysteresis loop measurements, and second harmonic generation measurements directly reveals the stabilization of the in-plane quasi-single-domain polarization state. This work offers design principles for engineering in-plane domains of ferroelectric oxide thin films, which is a prerequisite for high performance optoelectronic devices.