Size-dependent phase transition of V O2 nanostructures induced by light excitation

In nanocrystalline V O2 films the light-induced insulator-to-metal phase transition (I-M PT) dynamics was investigated by femtosecond optical pump-probe technique. The size of V O2 nanoparticles and the film morphology were found to be critical for the ultrafast light-induced PT dynamics as well as for thermal hysteresis. The I-M PT within subnanosecond scale demonstrates a nearly linear dependence of characteristic transition time on V O2 particles size. Such a behavior can indicate the importance of the phonon interactions with optically-excited electronic states.