Creating polar antivortex in PbTiO₃/SrTiO₃ superlattice

Nontrivial topological structures offer a rich playground in condensed matters and promise alternative device configurations for post-Moore electronics. While recently a number of polar topologies have been discovered in confined ferroelectric PbTiO₃ within artificially engineered PbTiO₃/SrTiO₃ superlattices, little attention was paid to possible topological polar structures in SrTiO₃. Here we successfully create previously unrealized polar antivortices within the SrTiO₃ of PbTiO₃/SrTiO₃ superlattices, accomplished by carefully engineering their thicknesses guided by phase-field simulation. Field- and thermal-induced Kosterlitz-Thouless-like topological phase transitions have also been demonstrated, and it was discovered that the driving force for antivortex formation is electrostatic instead of elastic. This work completes an important missing link in polar topologies, expands the reaches of topological structures, and offers insight into searching and manipulating polar textures.