Alexander Gray, SIMES
The electric-field control of conductivity in strongly-correlated oxides is currently considered to be one of the most promising avenues towards realizing next-generation energy-efficient electronic devices. We demonstrate that an ultrafast insulator-to-metal transition in thin epitaxial vanadium dioxide film can be induced by an intense electric-field pulse from a terahertz laser, and investigate the femtosecond-scale lattice and electronic structure dynamics of such electric-field-induced transition using LCLS-based time-resolved hard x-ray diffraction and THz-pump IR-probe measurements. The results reveal vastly different characteristic timescales for the electric-field-induced electronic structure switching happening virtually simultaneously with the sub-picosecond-scale THz pulse, in contrast with a much slower structural-transition dynamics occurring on tens-of-picoseconds timescale. Evidence of the transient conducting monoclinic phase is observed during the first few picoseconds following the THz pulse, suggesting that pure electronic-structure switching of conductivity in strongly-correlated oxides may be possible without energy-dissipative lattice transformations, which has a far-reaching impact on future energy-efficient electronic devices utilizing ultrafast electronic switching.The electric-field control of conductivity in strongly-correlated oxides is currently considered to be one of the most promising avenues towards realizing next-generation energy-efficient electronic devices. We demonstrate that an ultrafast insulator-to-metal transition in thin epitaxial vanadium dioxide film can be induced by an intense electric-field pulse from a terahertz laser, and investigate the femtosecond-scale lattice and electronic structure dynamics of such electric-field-induced transition using LCLS-based time-resolved hard x-ray diffraction and THz-pump IR-probe measurements. The results reveal vastly different characteristic timescales for the electric-field-induced electronic structure switching happening virtually simultaneously with the sub-picosecond-scale THz pulse, in contrast with a much slower structural-transition dynamics occurring on tens-of-picoseconds timescale. Evidence of the transient conducting monoclinic phase is observed during the first few picoseconds following the THz pulse, suggesting that pure electronic-structure switching of conductivity in strongly-correlated oxides may be possible without energy-dissipative lattice transformations, which has a far-reaching impact on future energy-efficient electronic devices utilizing ultrafast electronic switching.
