Fig. 1: Reversible electrical writing of 180°-DWs and their conduction response.

The three rows of images represent sequential scans of the same area (the a-domain crosshatch pattern being altered after each scan), cAFM maps are acquired with a 2V bias. a–d AFM-tapping mode topography, PFM and cAFM maps of a pristine area of the PZT film. The phase image confirms the uniform c-domain polarization and the cAFM maps reveals weak conduction traces at the position of 90°-DWs. f–i The same area after poling by an AFM-tip with −5 V tip bias applied. The switched 180° domains (purple regions in the phase map) are outlined by a high current response in the cAFM image. k–n Rescan of the same area after poling it back into the initial state by applying a tip bias of 5 V. The a-domain pattern visibly changes under the applied fields, the c-domains are poled back to the original state and no current at the former 180°-DW positions is detected. e, j Cross-section current profiles of cAFM maps as indicated in d and i averaged over 10 (blue) and 5 (red) lines respectively. o I–V characteristics probed by the AFM-tip that contacts the surface at the positions indicated in i on a 90°-DW (blue) and 180°-DW (red) together with the FN-fit (black).