Geometry-Controlled Switching Dynamics in VO₂ Networks

We investigated current-induced switching dynamics in networks of vanadium dioxide (VO₂), a correlated oxide that exhibits a metal–insulator transition near room temperature. Using lithographically defined VO₂ networks of varying lateral dimensions, we find that the current biased insulating to metal transition proceeds through discrete, step-like changes in resistance rather than a single sharp drop. Stepwise behavior appears only at the onset of the avalanche, whereas the return to the insulating state is characterized by a single abrupt transition. The magnitude of these steps scales systematically with the size of the VO₂ network: larger networks exhibit more pronounced jumps, whereas smaller networks reveal a finer sequence of smaller steps. With decreasing temperature, more steps are observed, suggesting that a larger fraction of network elements sequentially transition from insulating to metallic states. Using thermal imaging, we directly visualize the propagation of conductive filaments through the network and show how geometry influences the selection and evolution of percolation paths. Looking ahead, we aim to explore how adjacent VO₂ networks can "communicate" across an electrically insulating yet thermally transparent barrier, potentially enabling coupled phase dynamics relevant for neuromorphic and reconfigurable electronic architectures.