Filament dynamics in the voltage-driven insulator-to-metal transition*

Certain correlated oxides feature an insulator-to-metal transition which can be triggered by applying an external voltage: the material becomes conducting if a threshold electric field is exceeded. This phenomenon is known as voltage-driven IMT, and it has very promising applications in emerging technologies such as optoelectronics and neuromorphic computing. While it is known that this process takes place in a filamentary way, it is not yet known how these filaments nucleate, grow and relax. We combine reflectivity and transport measurements to image metallization with spatial and temporal resolution. Five correlated oxides from two different families are analyzed: VO₂, V₂O₃, V₃O₅, NdNiO₃ and SmNiO₃, finding remarkable differences in the filament expansion process. By comparing these systems and with the insight of numerical simulations, we identify the key parameters that govern the dynamics of the voltage-driven IMT.