Thickness-Dependent Polarization of Strained BiFeO3 Films with Constant Tetragonality

J. E. Rault, W. Ren, S. Prosandeev, S. Lisenkov, D. Sando, S. Fusil, M. Bibes, A. Barthélémy, L. Bellaiche, and N. Barrett
Phys. Rev. Lett. 109, 267601 – Published 26 December 2012
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Abstract

We measure the ferroelectric polarization of BiFeO3 films down to 3.6 nm using low energy electron and photoelectron emission microscopy. The measured polarization decays strongly below a critical thickness of 5–7 nm predicted by continuous medium theory whereas the tetragonal distortion does not change. We resolve this apparent contradiction using first-principles-based effective Hamiltonian calculations. In ultrathin films, the energetics of near open circuit electrical boundary conditions, i.e., an unscreened depolarizing field, drive the system through a phase transition from single out-of-plane polarization to nanoscale stripe domains. It gives rise to an average polarization close to zero as measured by the electron microscopy while maintaining the relatively large tetragonal distortion imposed by the nonzero polarization state of each individual domain.

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  • Received 17 May 2012

DOI:https://doi.org/10.1103/PhysRevLett.109.267601

© 2012 American Physical Society

Authors & Affiliations

J. E. Rault1, W. Ren2,3, S. Prosandeev2, S. Lisenkov4, D. Sando5, S. Fusil5,6, M. Bibes5, A. Barthélémy5, L. Bellaiche2, and N. Barrett1,*

  • 1CEA, DSM/IRAMIS/SPCSI, F-91191 Gif-sur-Yvette Cedex, France
  • 2Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA
  • 3Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444, China
  • 4Department of Physics, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620-5700, USA
  • 5Unité Mixte de Physique CNRS/Thales, 1 Avenue Augustin Fresnel, Campus de l’Ecole Polytechnique, 91767 Palaiseau, France and Université Paris-Sud, 91405 Orsay, France
  • 6Université d’Evry-Val d’Essonne, Boulevard François Mitterrand, 91025 Evry cedex, France

  • *To whom all correspondence should be addressed. nick.barrett@cea.fr

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Issue

Vol. 109, Iss. 26 — 28 December 2012

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