First-principles study of symmetry lowering in relaxed BaTiO3/SrTiO3 superlattices

The crystal structure and local spontaneous polarization of (BaTiO3)m/(SrTiO3)n superlattices is calculated using a first-principles density functional theory method. The in-plane lattice constant is 1% larger than the SrTiO3 substrate to imitate the relaxed superlattice structure and the symmetry i...

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Bibliographic Details
Published in:arXiv.org 2004-11
Main Authors: Johnston, Karen, Huang, Xiangyang, Neaton, Jeffrey B, Rabe, Karin M
Format: Article
Language:English
Subjects:
Barium titanates
Crystal structure
Density functional theory
First principles
Lattice parameters
Polarization
Strontium titanates
Substrates
Superlattices
Symmetry
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Summary:The crystal structure and local spontaneous polarization of (BaTiO3)m/(SrTiO3)n superlattices is calculated using a first-principles density functional theory method. The in-plane lattice constant is 1% larger than the SrTiO3 substrate to imitate the relaxed superlattice structure and the symmetry is lowered to monoclinic space group Cm which allows polarization to develop along the [110] and [001] directions. The polarization component in the [110] direction is found to develop only in the SrTiO3 layers and falls to zero in the BaTiO3 layers, whereas the polarization in the [001] direction is approximately uniform throughout the superlattice. These findings are consistent with recent experimental data and first-principles results for epitaxially strained BT and ST.
ISSN:2331-8422
DOI:10.48550/arxiv.0411593