Piezoelectric response of epitaxial ferroelectric heterostructures

The electromechanical response of epitaxial oxide heterostructures can be used to probe novel properties arising from nanoscale structural confinement. To resolve the layer-by-layer origin of piezoelectric responses of ferroelectric/dielectric superlattices, we performed time-resolved x-ray microdiffraction studies of a 2(BaTiO$_{3})$/4(CaTiO$_{3})$ superlattice in an applied electric field. The contributions of individual components to the overall piezoelectric response are deduced using kinematic x-ray diffraction calculations. We found that the dielectric CaTiO$_{3}$ component has an equal piezoelectric response and remnant polarization to the ferroelectric BaTiO$_{3}$ component, in good agreement with predictions of piezoelectric coefficient ($\sim $50 pm/V) and local polarization distribution based on density functional theory calculations.