Geometry confined polar vertex domains in self-assembled BiFeO3 nano-islands

ABSTRACT Low-dimensional ferroelectric topological textures show abundant configurations such as flux-closure quadrants and vortices, suggesting potential applications in nano-electronic devices. However, the deterministic control of those polar textures is still challenging. By using piezoresponse force microscopy, threefold or fourfold vertex domain structures were observed in self-assembled BiFeO3 nano-islands, and the formation of such polar topological textures is strongly dependent on the size and shape of the nano-island. Furthermore, the vertex domain textures confined by geometry can be reversibly switched back and forth by external electric field, which are stabilized by the competition between elastic energy and electrostatic energy. GRAPHICAL ABSTRACT IMPACT STATEMENT Stable threefold or fourfold vertex domain structures are formed on BiFeO3 nano-islands, depending on the size and shape of the nanoisland