Origin of the current-driven breakdown in vanadium oxides: Thermal versus electronic

We report the existence of two competing mechanisms in the current-driven electrical breakdown of vanadium sesquioxide (V2O3) and vanadium dioxide (VO2) nanodevices. Our experiments and simulations show that the competition between a purely electronic (PE) mechanism and an electrothermal (ET) mechanism, suppressed in nanoscale devices, explains the current-driven insulator-to-metal phase transition (IMT). We find that the relative contribution of PE and ET effects is dictated by thermal coupling and resistivity, a discovery which disambiguates a long-standing controversy surrounding the physical nature of the current-driven IMT in vanadium oxides. Furthermore, we show that the electrothermally driven IMT occurs through a nanoscopic surface-confined filament. This nanoconfined filament has a very large thermal gradient, thus generating a large Seebeck-effect electric field.