Thickness-dependent polarization of strained BiFeO3 films with constant tetragonality

Abstract

We measure the remnant polarization of ferroelectric domains in 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 ultra thin films the energetics of near open circuit electrical boundary conditions, i.e. unscreened depolarizing field, drive the system through a phase transition from single out-of-plane polarization to a nanoscale stripe domains, giving rise to an average remnant polarization close to zero as measured by the electron microscopy whilst maintaining the relatively large tetragonal distortion imposed by the non-zero polarization state of each individual domain.

main article: 5 pages, 6 figures; supplementary materials: 6 pages, 6 figures. Published in Phys. Rev. Lett

References in corpus (4)

• Fractal dimension and size scaling of domains in thin films of multiferroic BiFeO3
• Effect of epitaxial strain on ferroelectric polarization in multiferroic BiFeO3 films
• Depolarizing-Field Effect in Strained Nanoscale Ferroelectric Capacitors and Tunnel Junctions
• Monodomain to polydomain transition in ferroelectric PbTiO3 thin films with La0.67Sr0.3MnO3 electrodes

Cited by in corpus (3)

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