Andrea Cavalleri

Abstract:

We report on the study of the ultrafast insulator-to-metal transition in nanoparticles of strongly correlated VO2. The particles are grown by ion-implantation and self-assembly in a Silica matrix and can be switched between the insulating and metallic phase within less than 100 fs. The prompt formation of the metallic state results in the appearance of a surface-plasmon resonance that is absent in the bulk and can be further tailored by controlling the particle shape.

Abstract:

In the last few years the generation of femtosecond pulses in the X-ray regime has become possible. These ultrashort X-ray pulses have enabled femtosecond time-resolution to be extended to X-rays.

Abstract:

We establish a time-domain hierarchy between structural and electronic effects in the model strongly correlated system VO2. We find that the insulator-to-metal transition is driven directly by structural change rather than by electron-electron correlations.

Abstract:

The photo-induced insulator-to-metal transition in VO2, is measured with 15-fs, μJ pulses. Our measurements allow for the separation of structural and electronic effects in this heavily debated compound.

Abstract:

We measure the insulator-to-metal transition in VO2 using time-resolved Near-Edge X-ray Absorption. Picosecond pulses of synchrotron radiation are used to detect the red-shift in the Vanadium L3 edge at 516 eV, associated with bandgap collapse.