Optically induced coherent voltage oscillations in K0.3MoO3

Optical induced transient changes of the electrical conductivity are investigated in the non-linear transport regime of the blue bronze K0.3MoO3 below its Peierls transition using the impulsive infrared excitation of a free-electron laser at energies above the Peierls gap. The transients of the sample voltage have typical relaxation times of 0.5-2 ms superimposed by coherent voltage oscillations, which exhibit lifetimes of up 100 ms. The frequency of those voltage oscillation is found to be time dependent. This, in comparison with voltage oscillations purely driven by static electrical fields, enables the study of quasiparticle dynamics in the charge density condensate of the blue bronze