Probing Enhanced Ferroelectricity in Strained SrTiO3 and BaTiO3 Epitaxial Films using optical Second Harmonic Generation

This talk will present real-time second harmonic generation (SHG) experiments used for \textit{in-situ} probing of ferroelectric domain reversal and phase transitions in \textit{strained} SrTiO$_{3}$ and BaTiO$_{3}$ epitaxial thin films grown commensurately on scandate substrates such as GdScO$_{3}$ and DyScO$_{3}$. The Curie temperature, T$_{c}$ shifts by hundred of degrees because of the compressive strains (up to -1.5{\%}) imparted to these films. Using SHG we find that Tc shifts to $\sim $27C in SrTiO$_{3}$ (which normally is not ferroelectric at any temperature) and to $\sim $650C for BaTiO$_ {3}$ thin films on DyScO$_{3}$ as compared to T$_{c}$ of 120C in bulk crystals. Studies on real-time dynamics of domain reversal under external fields in these strained films beyond their normal Curie temperatures where domains are not expected at all would also be presented.