Lattice screening of the polar catastrophe and hidden in-plane polarization in KNbO3/BaTiO3 interfaces

Pablo García-Fernández*, Pablo Aguado-Puente, Javier Junquera

*Corresponding author for this work

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

We have carried out first-principles simulations, based on density functional theory, to obtain the atomic and electronic structure of (001) BaTiO3/KNbO3 interfaces in an isolated slab geometry. We tried different types of structures including symmetric and asymmetric configurations and variations in the thickness of the constituent materials. The spontaneous polarization of the layer-by-layer non-neutral material (KNbO 3) in these interfaces cancels out almost exactly the "built-in" polarization responsible for the electronic reconstruction. As a consequence, the so-called polar catastrophe is quenched and all the simulated interfaces are insulating. A model, based on the modern theory of polarization and basic electrostatics, allows an estimation of the critical thickness for the formation of the two-dimensional electron gas between 33 and 36 KNbO3 unit cells. We also demonstrate the presence of an unexpected in-plane polarization in BaTiO3 localized at the p-type TiO2/KO interface, even under in-plane compressive strains. We expect this in-plane polarization to remain hidden due to angular averaging during quantum fluctuations unless the symmetry is broken with small electric fields.

Original languageEnglish
Article number085305
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume87
Issue number8
DOIs
Publication statusPublished - 13 Feb 2013
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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