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Finite-size effects in lead scandium tantalate relaxor thin films

Abel Fernandez, Jieun Kim, Derek Meyers, Sahar Saremi, and Lane W. Martin
Phys. Rev. B 101, 094102 – Published 4 March 2020
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Abstract

Large electromechanical effects in relaxor ferroelectrics are generally attributed to the collective response of an ensemble of correlated, nanometer-sized polar structures induced by chemical and charge disorder. Here, we study finite-size effects on such polar order (i.e., how it evolves when sample dimensions approach the polarization correlation length) in 7–70-nm-thick films of the relaxor ferroelectric PbSc0.5Ta0.5O3. Temperature-dependent polarization studies reveal a linear suppression of the polarization and nonlinearity associated with relaxor order as the film thickness decreases to 30 nm. Below this thickness, however, the suppression rapidly accelerates, and polarization is completely absent by film thicknesses of 7 nm, despite the continued observation of a broad peak in dielectric permittivity and frequency dispersion. Diffuse-scattering measurements reveal the diffuse-scattering symmetry, and analysis suggests the films have a polarization correlation length of 23 nm. Taken together, it is apparent that reduction of sample size and the resulting distribution of polar structures drive suppression and eventual quenching of the electrical response of relaxors, which may be attributed to increasing dipole-dipole and dipole-interface interactions.

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  • Received 21 November 2019
  • Revised 5 February 2020
  • Accepted 19 February 2020

DOI:https://doi.org/10.1103/PhysRevB.101.094102

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Abel Fernandez1, Jieun Kim1, Derek Meyers1,*, Sahar Saremi1, and Lane W. Martin1,2,†

  • 1Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
  • 2Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

  • *Present address: Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, USA.
  • lwmartin@berkeley.edu

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Issue

Vol. 101, Iss. 9 — 1 March 2020

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