Room-temperature electro-optic properties of strained $SrTiO3$ films grown on $DyScO3$

The electro-optic response of epitaxially strained $SrTiO3$ grown on bulk $DyScO3$ substrates is measured as a function of applied in-plane bias (both magnitude and direction) and light polarization. The effective electro-optic coefficients are bias-field dependent. Hysteresis is observed at room temperature, indicative of residual polarity, which is believed to be due to long-lived alignment of nanopolar regions possibly due to defects. A simple model incorporating non-$180°$-nanoscale domains can account for most of the experimental observations.