Coherent structural dynamics and electronic correlations during an ultrafast insulator-to-metal phase transition in VO2.
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.
Kübler
C
C
Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany.
Ehrke
H
H
Huber
R
R
Lopez
R
R
Halabica
A
A
Haglund
R F
RF
Leitenstorfer
A
A