The effect of stoichiometry on the dielectric properties and soft mode behavior of strained epitaxial Sr1+xTiO3+ δ 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 sharp maximum and pronounced soft mode behavior. Our results suggest that strained perfectly stoichiometric SrTiO 3 films should not show relaxor behavior and that relaxor behavior emerges from defect dipoles that arise from non-stoichiometry in the highly polarizable strained SrTiO3 matrix.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)