Electric field control of antiferroelectric domain pattern

Control of domain and domain wall configurations in antiferroelectrics is a necessary step towards practical use of new functionalities based on polar domain wall structures. Here we propose and demonstrate a domain engineering scheme that provides an antiferroelectric state with only one type of orientational domains and one type of walls. We demonstrate with in situ synchrotron diffraction experiment that in a material, where the transition from the high-symmetry nonpolar phase to that antiferroelectric occurs via crossing an intermediate, once the transition is passed under a moderate electric field, the final antiferroelectric domain state can be fully controlled. A theoretical analysis shows that such a phenomenon can be explained in terms of biquadratic coupling between the polarization and antiferroelectric order parameter. This analysis also suggests that the electric-field control of the antiferroelectric state may be possible in a more general case where the intermediate ferroelectric state is absent. Anisotropy of lattice excitations in the intermediate polar phase under electric field is uncovered by an inelastic x-ray scattering experiment, which indicates that lattice instability is a driving force of transformation towards antiferroelectric phase despite of a strong first character of the transition.