Ferroelastic domain motion by pulsed electric field in (111)/(111¯) rhombohedral epitaxial Pb(Zr0.65Ti0.35)O3 thin films: Fast switching and relaxation

Reversible electric-field induced domain switching in ferroelectric thin films gives rise to a large electromechanical coupling. Despite extensive in situ studies confirming a dominant contribution from domain switching, the speed of the domain wall motion had not been discussed enough. In this study, we performed time-resolved measurement of lattice elongation and non-180\ifmmode^\circ\else\textdegree\fi{} domain switching for an epitaxial rhombohedral $(111)/(11\overline{1})$-oriented ($\mathrm{Pb}(\mathrm{Z}{\mathrm{r}}_{0.65}\mathrm{T}{\mathrm{i}}_{0.35}){\mathrm{O}}_{3}$ film under nanosecond electric field pulses by means of synchrotron x-ray diffraction. Both lattice elongation and non-180\ifmmode^\circ\else\textdegree\fi{} domain switching due to a 200-ns electric pulse were directly observed from the shift of the 222 diffraction position toward a lower angle and the change in the integrated intensity ratio of 222 to $22\overline{2}$ peaks, respectively. The non-180\ifmmode^\circ\else\textdegree\fi{} domain switching also results in an increase of the switchable polarization. Following the removal of the electric field, it is seen that the non-180\ifmmode^\circ\else\textdegree\fi{} domain back switching from 222 to $22\overline{2}$ is sluggish compared to the relaxation of the field-induced lattice strain. This is different from the (100)/(001)-oriented tetragonal epitaxial $\mathrm{Pb}(\mathrm{Zr},\mathrm{Ti}){\mathrm{O}}_{3}$ films, in which no obvious delay was detected. These results show the importance of the direct time-resolved response observation of the crystal structure change with the application of a high-speed electric pulse field to understand the frequency dispersion of the ferroelectric and piezoelectric responses of $\mathrm{Pb}(\mathrm{Zr},\mathrm{Ti}){\mathrm{O}}_{3}$ films.