Deterministic switching between flux-closure and center-type polar topological structures via modulation of oxygen vacancies

Deterministic control of polar topological structures has attracted considerable attention due to its potential applications in post-Moore electronics. While manipulation techniques such as strain (via substrates), electric fields, and temperature are commonly employed, switching induced by charged defects between different polar topological structures remains a rarely observed phenomenon. In this study, we demonstrate that oxygen vacancies can effectively enable the switching between flux-closure and center-type topological structures in PbTiO3 (PTO) nano-island arrays. Supported by evidence from x-ray photoelectron spectroscopy, scanning Kelvin probe microscopy, and piezoresponse force microscopy, we demonstrate that a high concentration of oxygen vacancies favors the formation of center-type domains, while the topological structure transitions to the flux-closure configuration following elimination of oxygen vacancies via in situ annealing under various gas atmospheres. This deterministic switching between the two polar topological structures highlights the critical role of charged defects and opens new avenues for the manipulation of polar topological structures in future applications.