THz Slow Motion of an Ultrafast Insulator-Metal Transition in VO2 : Coherent Structural Dynamics and Electronic Correlations
2009, Huber, Rupert, Kübler, Carl, Ehrke, Henri, Lopez, Ricardo, Halabica, Andrej, Haglund, Richard F., Leitenstorfer, Alfred
The multi-THz conductivity of VO2 recorded during a photoinduced insulator-metal transition directly reveals the femtosecond dynamics of V-V stretching modes and electronic correlations. We suggest a novel qualitative model for the nonthermal phase transition.
Coherent structural dynamics and electronic correlations during an ultrafast insulator-to-metal phase transition in VO2
2007, Kübler, Carl, Ehrke, Henri, Lopez, Rene, Halabica, Andrej, Haglund, Richard F., Leitenstorfer, Alfred
We directly trace the multi-THz conductivity of VO2 during an insulator-metal transition triggered by a 12-fs light pulse. The femtosecond dynamics of lattice and electronic degrees of freedom are spectrally discriminated. A coherent wave packet motion of V-V dimers at 6 THz modulates the lattice polarizability for approximately 1 ps. In contrast, the electronic conductivity settles to a constant value already after one V-V oscillation cycle. Based on our findings, we propose a qualitative model for the nonthermal phase transition.