Abstract
We report on growth and ferroelectric (FE) properties of superlattices (SLs) composed of the FE BaTiO3 and the paraelectric CaTiO3. Previous theories have predicted that the polarization in (BaTiO3)n/(CaTiO3)n SLs increases as the sublayer thickness (n) increases when the same strain state is maintained. However, our BaTiO3/CaTiO3 SLs show a varying lattice-strain state and systematic reduction in polarization with increasing n while coherently strained SLs with n=1 and 2 show a FE polarization of ca. 8.5 μC/cm2. We suggest that the strain coupling plays a more important role in FE properties than the electrostatic interlayer coupling based on constant dielectric permittivities.
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