fig7

Figure 7. (A) Optical microscopy images of wrinkled BTO. The scale bar is 20 µm. (B) Piezoresponse force microscopy (PFM) phase color images of zigzag-wrinkled BTO under scanning force induced by the SPM tip. (C) Distribution of corresponding strain component ε_xx of zigzag-wrinkled BTO by the SPM tip from phase-field simulations considering the flexoelectric effect. (D) Distribution of “braided-like” polarization of zigzag-wrinkled BTO by the SPM tip. The color bar represents the polarization component P_x. (E) IP-PFM phase image showing the toroidal polar topology of wrinkled P(VDF-TrFE) film. (F and G) The in-plane strain and domain structure of the wrinkled P(VDF-TrFE) under an applied tensile strain of 7.3% from phase-field simulations, respectively. (H) The electric toroidal moments corresponding to the domain structure in (G) illustrate the presence of in-plane topological domains. Panel A reprinted with permission^[63]. Copyright 2020, Wiley-VCH. Panels B-D reprinted with permission^[64]. Copyright 2022, American Chemical Society. Panels E-H reprinted with permission^[65]. Copyright 2021, The American Association for the Advancement of Science.