Fig. 3: Imaging of filamentary resistive switching.

a Typical resistivity hysteresis of a V₂O₃ film. Adapted from ref. ⁷⁵. b Typical current-voltage curve of a V₂O₃ device, sketched on the top, where resistive switching occurs at 0.9 mA upon driving of a current across a 2 μm gap. c Wide-field optical microscopy photomicrographs of a V₂O₃ device acquired simultaneously to a current sweep. A narrow metallic filament (dark line) connecting the electrodes appears above the threshold current for the switching (panel B) and widens for increasing currents (panels C, D). When the current is decreased, the metallic channel splits into multiple filaments (panel E–H) until disappearing when the current is removed and the device returns to an insulating state. Adapted from ref. ⁷⁴. d Resistivity hysteresis in nickel oxide thin films. Adapted from ref. ⁷⁶. e Current-voltage curves measured in a NdNiO₃ device at different temperatures. Adapted from ref. ⁷⁶. f Wide-field optical microscopy images of the metallic filament forming in a NdNiO₃ device upon application of an above threshold 20 mA current at temperature T = 80 K (left) and T = 50 K (right). Adapted from ref. ⁷⁶.