High-density ferroelectric BiFeO3 (BFO) nanodot arrays were developed through template-assisted tailoring of epitaxial thin films. By combining piezoresponse force microscopy (PFM) and Kelvin probe force microscopy (KPFM) imaging techniques, we found that oxygen vacancies in nanodot arrays can be transported in the presence of an electric field. Besides triple-center domains, quadruple-center domains with different vertical polarizations were also identified. This was confirmed by combining the measurements of the domain switching and polarization vector distribution. The competition between the accumulation of mobile charges, such as oxygen vacancies, on the interface and the geometric constraints of nanodots led to the formation of these topological domain states. These abnormal multi-center topological defect states pave the way for improving the storage density of ferroelectric memory devices.

Ferroelectric stripe domain structure and domain walls were investigated by vector PFM on epitaxial BiFeO3 thin films. Measurements of topography of film versus distance between spikes, we identify the [Formula: see text] domain in the film, were supported by XRD and AFM characterization. [Formula: see text] domain can be switched under the electric field engendered by the biased PFM tip, and their controllable [Formula: see text] rotation can be maintained by electron injection by the PFM tip. These stripe domain walls are conductive, provide an opportunity to further study their new properties in high-density memory devices.

This article reports on using atomic force microscopy to investigate the structure and switching of ferroelectric domains on nanodot arrays. High‐density arrays of epitaxial discrete nanodots are fabricated by the template‐assisted tailoring of thin films. Furthermore, the measurement of the vectorial polarization distribution and switching of domains is conducted, which helps identify four topological domain states. In addition to convergent and divergent domain states with upward and downward polarization, double‐center and triple‐center domains are identified. Thus, the study shows the formation mechanisms for these topological domain states using the accumulation of mobile charges on the interface and the strain gradient arising from the tailoring of thin films into nanodots. The properties of these exotic multicenter topological domain states provide the opportunity to further study their potential application in high‐density storage devices.