In-situ observation of ultrafast 90° domain switching under application of an electric field in (100)/(001)-oriented tetragonal epitaxial Pb(Zr<inf>0.4</inf>Ti<inf>0.6</inf>)O<inf>3</inf> thin films

Ferroelastic domain switching significantly affects piezoelectric properties in ferroelectric materials. The ferroelastic domain switching and the lattice deformation of both a-domains and c-domains under an applied electric field were investigated using in-situ synchrotron X-ray diffraction in conjunction with a high-speed pulse generator set up for epitaxial (100)/(001)-oriented tetragonal Pb(Zr0.4Ti0.6)O3 (PZT) films grown on (100) c SrRuO3//(100)KTaO3 substrates. The 004 peak (c-domain) position shifts to a lower 2θ angle, which demonstrates the elongation of the c-axis lattice parameter of the c-domain under an applied electric field. In contrast, the 400 peak (a-domain) shifts in the opposite direction (higher angle), thus indicating a decrease in the a-axis lattice parameter of the a-domain. 90° domain switching from (100) to (001) orientations (from a-domain to c-domain) was observed by a change in the intensities of the 400 and 004 diffraction peaks by applying a high-speed pulsed electric field 200 ns in width. This change also accompanied a tilt in the angles of each domain from the substrate surface normal direction. This behaviour proved that the 90° domain switched within 40 ns under a high-speed pulsed electric field. Direct observation of such high-speed switching opens the way to design piezo-MEMS devices for high-frequency operation

Ferroelastic domain motion by pulsed electric field in (111)/(11 1) rhombohedral epitaxial Pb(Z r0.65 T i0.35) O3 thin films: Fast switching and relaxation FERROELASTIC DOMAIN MOTION by PULSED ... YOSHITAKA EHARA et al.

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° domain switching for an epitaxial rhombohedral (111)/(111)-oriented (Pb(Zr0.65Ti0.35)O3 film under nanosecond electric field pulses by means of synchrotron x-ray diffraction. Both lattice elongation and non-180° 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 222 peaks, respectively. The non-180° 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° domain back switching from 222 to 222 is sluggish compared to the relaxation of the field-induced lattice strain. This is different from the (100)/(001)-oriented tetragonal epitaxial Pb(Zr,Ti)O3 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 Pb(Zr,Ti)O3 films