Static structures and dynamic responses of polar topologies in oxide superlattices

Polar topologies in ferroelectric/paraelectric superlattices have been an important substance to explore exotic physical properties. Although enormous efforts have been paid to this field, the universality of the formation of polar topologies in various superlattices and their electric field dynamics is still unknown. Herein, we employ a phase-field model to construct three types of ferroelectric/paraelectric superlattices with tetragonal, rhombohedral, and orthorhombic symmetries and investigate their static structures and dynamic responses as a function of epitaxial strain. It is found that all superlattices undergo a similar vortex-spiral-in-plane topology transition, which corresponds to peaked dielectric permittivity curves and ferroelectric-, antiferroelectric-, and paraelectric-like hysteresis loops. Such polarization behaviors are attributed to the triple-well free energy landscape. The flexibility of hysteresis loops generates high energy density and efficiency of ferroelectric/paraelectric superlattices. This study offers a systematic view of the generality of polar topologies in multilayered ferroelectrics.