Abstract
The effect of stoichiometry on the dielectric properties and soft mode behavior of strained epitaxial
Sr1-xTiO3 films grown on DyScO3 substrates is reported. Direct comparisons between nominally
stoichiometric and non-stoichiometric films have been performed through measurements of lattice
parameters, temperature-dependent permittivities, second harmonic generation, and terahertz dielectric spectra. The nominally stoichiometric film shows dispersion-free low-frequency permittivity with a
23 sharp maximum and pronounced soft mode behavior. Our results suggest that strained perfectlystoichiometric SrTiO3 films should not show relaxor behavior and that relaxor behavior emergesfrom defect dipoles that arise from non-stoichiometry in the highly polarizable strained SrTiO3 matrix