Flexoelectric effect via piezoresponse force microscopy of domain switching in epitaxial PbTiO3 thin films

The flexoelectric effect can be exploited to control the polarization and domain structure in ferroelectric materials, potentially benefiting applications, such as nanoscale electromechanical systems, memory devices, and sensors. We report ferroelectric domain switching characteristics of PbTiO3 (PTO) thin films induced by the flexoelectric effect. Epitaxially (001)-oriented PbTiO3 (PTO) thin films were deposited on single-crystal Nb-doped SrTiO3 substrates by pulsed laser deposition. Through the use of a piezoelectric force microscope and two surface electrodes, polarization domains were created vertically and horizontally within the PTO film. When subjected to a vertical external force, the domains with vertical orientation exhibited predictable switching behavior. Conversely, by imposing a vertical force during the scanning of domains oriented horizontally, we observed the formation of new domains with vertical orientation. However, in conditions where a vertical force was applied counter to the alignment of the horizontal domains, the anticipated switching of the vertical domains did not manifest. This study demonstrates that the flexoelectric effect can be harnessed to manipulate the switching of ferroelectric domains in PTO thin films using piezoresponse force microscopy.