Phase transitions and polarizations in epitaxial BaTiO3/SrTiO3 superlattices studied by second-harmonic generation
2002; American Institute of Physics; Volume: 93; Issue: 2 Linguagem: Inglês
10.1063/1.1533094
ISSN1520-8850
AutoresAnquan Jiang, J. F. Scott, Huibin Lu, Zhenghao Chen,
Tópico(s)Photorefractive and Nonlinear Optics
ResumoBaTiO 3 / SrTiO 3 superlattices are found to have a critical periodicity of 30 SrTiO3 unit cells, below which the room-temperature symmetry is mm2 orthorhombic. The orthorhombic-tetragonal phase-transition temperature is shifted upward from the bulk value (<3 K and normally not observed at finite temperature) of the quantum paraelectric pure strontium titanate to temperatures above ambient (599 K for 30/30-unit-cell superlattices). Antidipole patterns appear in superlattices with unit cells below 10/10. A model is presented that accounts quantitatively for the change in second-harmonic generation intensity with superlattice periodicity from 4 unit cells to 50.
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