Strain dependencies of energetic, structural, and polarization properties in tetragonal (PbTiO3)1/(SrTiO3)1 and (BaTiO3)1/(SrTiO3)1 superlattices: a comparative study with bulks

摘要

First-principles density functional calculations are performed to investigatethe interplay between inplane strains and interface effects in 1by1PbTiO3/SrTiO3 and BaTiO3/SrTiO3 superlattices of tetragonal symmetry. Oneparticular emphasis of this study is to conduct side-by-side comparisons onvarious ferroelectric properties in short-period superlattices and inconstituent bulk materials, which turns out to be rather useful in terms ofobtaining valuable insight into the different physics when ferroelectric bulksform superlattices. The various properties that are studied in this workinclude the equilibrium structure, strain dependence of mixing energy,microscopic ferroelectric off-center displacements, macroscopic polarization,piezoelectric coeffcients, effective charges, and the recently formulatedk-dependent polarization dispersion structure. The details of our findings arerather lengthy, and are summarized in Sec. IV.