paper

Theory of polarization enhancement in epitaxial BaTiO/SrTiO superlattices

arXiv:cond-mat/0211421 · doi:10.1063/1.1559651

Abstract

The spontaneous polarization of epitaxial BaTiO/SrTiO superlattices is studied as a function of composition using first-principles density functional theory within the local density approximation. With the in-plane lattice parameter fixed to that of bulk SrTiO, the computed superlattice polarization is enhanced above that of bulk BaTiO for superlattices with BaTiO fraction larger than 40%. In contrast to their bulk paraelectric character, the SrTiO layers are found to be {\it tetragonal and polar}, possessing nearly the same polarization as the BaTiO layers. General electrostatic arguments elucidate the origin of the polarization in the SrTiO layers, with important implications for other ferroelectric nanostructures.

arXiv comment4 pages, 2 Figures, 1 Table

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