Ultrafast terahertz field control of electronic and structural interactions in vanadium dioxide

Abstract

In this study, the authors show that multiple interrelated processes in the nonequilibrium electronic and structural dynamics in vanadium dioxide can be disentangled experimentally in the time domain. This is accomplished by using both near-infrared and hard x-ray pulses to track the dynamics following excitation with an intense nonresonant terahertz pulse, which initiates the insulator-metal transition. Electronic structure switching is observed to be virtually simultaneous with the subpicosecond metamaterial-enhanced terahertz pulse; it is induced by electric-field-assisted tunneling of valence electrons into the conduction band. For sufficiently high electric fields, this triggers the onset of the full transition to the rutile metallic state.