Optically Induced Picosecond Lattice Compression in the Dielectric Component of a Strongly Coupled Ferroelectric/Dielectric Superlattice

Above-bandgap femtosecond optical excitation of a ferroelectric/dielectric BaTiO3/CaTiO3 superlattice leads to structural responses that are consequence the screening strong electrostatic coupling between component layers. Time-resolved x-ray free-electron laser diffraction shows response includes net lattice expansion consistent with depolarization-field driven by photoexcited charge carriers. The depolarization-field-screening-driven is separate from photoacoustic pulse launched bottom electrode on which was epitaxially grown. distribution diffracted intensity reflections indicates depolarization-field-screening-induced strain photoinduced in ferroelectric BaTiO3 and contraction CaTiO3. magnitude layers larger than difference CaTiO3 components can arise contribution oxygen octahedral rotation patterns at interfaces polarization reduction points new direction for manipulation strongly coupled superlattice.