Current-induced Nonequilibrium Phase Transition Accompanied by Giant Gap Reduction in Vanadium Dioxide

TL;DR

This study reveals that applying a steady current to bulk VO2 crystals induces a nonequilibrium insulator-metal transition with a giant gap reduction, highlighting a nonthermal electronic control mechanism distinct from thermal effects.

Contribution

It demonstrates a current-induced phase transition in bulk VO2 with a significantly lower electric field than thin films, emphasizing an intrinsic electronic origin.

Findings

Current induces insulator-metal transition in VO2

Electric field required is much lower than in thin films

Transition occurs without significant heating

Abstract

We investigated nonlinear conduction in bulk single crystals of VO2 with precise temperature control. Two distinct nonequilibrium phenomena were identified: a gradual reduction of the charge gap and a current-induced insulator-metal transition. The electric field required to drive the nonlinear conduction is two to three orders of magnitude smaller than that reported for VO2 thin films or nanobeams, strongly indicating an intrinsic electronic origin rather than a temperature increase due to self heating. Notably, our results suggest that the application of a steady current to the frozen insulating state can induce a nonequilibrium steady-state metallic phase -- effectively melting the electronic ice. This highlights a novel route to controlling electronic states via nonthermal, current-driven mechanisms.