We visualize an electric-field-induced collective propagation of oxygen vacancies spontaneously contained in Ca-substituted BiFeO3 films, using the fact that the oxygen-rich and poor regions have different color contrasts and thus they are optically distinguishable forming a sharp boundary. We quantitatively determine the drift velocity to be of the order of 100 μm s−1 with an activation barrier of 0.79 eV indicating a significantly large ionic mobility 2 × 10−6 cm2 s−1 V−1 at a remarkably low temperature of 390 °C. Furthermore, U-shaped propagation and turbulence under backward electric field provide insights into fluidic defects in crystalline solids.
- Ji Soo Lim
- Jin Hong Lee
- Chan-Ho Yang
