Strain fluctuations in BaTiO₃/SrTiO₃ heterostructures
Gartnerova, V.; Pacherova, O.; Klinger, M.; Jelinek, M.; Jager, A.; Tyunina, M. (2017-05-01)
V. Gartnerova, O. Pacherova, M. Klinger, M. Jelinek, A. Jager, M. Tyunina, Strain fluctuations in BaTiO3/SrTiO3 heterostructures, Materials Research Bulletin, Volume 89, 2017, Pages 180-184, ISSN 0025-5408, https://doi.org/10.1016/j.materresbull.2017.01.048.
© 2017 Elsevier Ltd. All rights reserved. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/.
https://creativecommons.org/licenses/by-nc-nd/4.0/
https://urn.fi/URN:NBN:fi-fe2019051315368
Tiivistelmä
Abstract
Epitaxy of perovskite oxide ferroelectric heterostructures with large lattice misfit is crucial for numerous emerging applications. Here we demonstrate cube-on-cube-type epitaxial growth of BaTiO₃ films on strongly mismatched (001)SrTiO₃ single-crystal substrates for the films with thicknesses significantly larger than that of misfit relaxation. The films experience strain originating from the film-substrate thermal expansion mismatch. Using a dedicated digital analysis of electron microscopy images, we show that the films contain random nanoregions of substantial strain fluctuations: the local strains vary in the range of ∼(0.5–2)% compared with the average strain magnitude of ∼1%. Because of strong strain-polarization coupling in ferroelectrics, fluctuations of strain produce fluctuations of polarization, which are suggested to cause relaxor-like properties in many mismatched heterostructures.
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