Influence of Flexoelectric Effects on Current-voltage Characteristic of Polydomain in Ferroelectric Thin Films

Strain gradients at domain walls in polydomain ferroelectric thin films generally are huge, reaching a value of 10⁷-10⁸ m^-1, appears at domain walls. These huge strain gradients always play a considerable impact on polarization distribution via flexoelectricity. However, the ability of the flexoelectricity to tune the leakage current in ferroelectric nanofilms is untouched to date. By combining the phase field model and diffusion equations for an electron/electron hole, a self-consistent model is established to investigate the influence of flexoelectric effect on the current-voltage characteristic of Pt/Pb(Zr_0.1Ti_0.9)O₃/Pt capacitor. It is shown that the longitudinal flexoelectric coefficient related coupling type would reduce the electric potential, and thus, increase the electron hole concentration and cause leakage current increasing in thin films. In contrast, the transverse flexoelectric coefficient related coupling type would raise the electric potential, decrease the electron hole concentration and cause leakage current decreasing in thin films.