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Abstract: First-principles modeling of ferroelectric capacitors presents severaltechnical challenges, due to the coexistence of metallic electrodes, long-rangeelectrostatic forces and short-range interface chemistry. Here we show howthese aspects can be efficiently and accurately rationalized by using afinite-field density-functional theory formalism in which the fundamentalelectrical variable is the displacement field D. By performing calculations onmodel Pt-BaTiO3-Pt and Au-BaZrO3-Au capacitors we demonstrate how theinterface-specific and bulk-specific properties can be identified andrigorously separated. Then, we show how the electrical properties of capacitorsof arbitrary thickness and geometry symmetric or asymmetric can be readilyreconstructed by using such information. Finally, we show how usefulobservables such as polarization and dielectric, piezoelectric andelectrostrictive coefficients are easily evaluated as a byproduct of the aboveprocedure. We apply this methodology to elucidate the relationship betweenchemical bonding, Schottky barriers and ferroelectric polarization atsimple-metal-oxide interfaces. We find that BO2-electrode interfaces behaveanalogously to a layer of linear dielectric put in series with a bulk-likeperovskite film, while a significant non-linear effect occurs at AO-electrodeinterfaces.



Autor: Massimiliano Stengel, David Vanderbilt, Nicola A. Spaldin

Fuente: https://arxiv.org/







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