Current oscillations in vanadium dioxide: Evidence for electrically triggered percolation avalanches

In this work, we experimentally and theoretically explore voltage-controlled oscillations occurring in microbeams of vanadium dioxide. These oscillations are a result of the reversible insulator-to-metal phase transition in vanadium dioxide. By examining the structure of the observed oscillations in detail, we propose a modified percolative-avalanche model which allows for voltage triggering. This model captures the periodicity and waveshape of the oscillations as well as several other key features. Importantly, our modeling shows that while temperature plays a critical role in the vanadium dioxide phase transition, electrically induced heating can not act as the primary instigator of the oscillations in this configuration. This realization leads us to identify the electric field as the most likely candidate for driving the phase transition.