Ultrafast phase-transition induced by selective vibrational excitation in a magnetoresistive manganite
Conference on Quantum Electronics and Laser Science (QELS) - Technical Digest Series (2008)
Abstract:
We show that selective excitation of a phonon mode induces an insulator-metal phase transition in a magnetoresistive manganite. The dynamics of such phase transformation are studied by optical pump-probe, transport and X-ray absorption measurements. © 2008 Optical Society of America.Erratum: Ultrafast single-shot diffraction imaging of nanoscale dynamics
Nature Photonics Springer Nature 2:9 (2008) 578-578
Ultrafast single-shot diffraction imaging of nanoscale dynamics
Nature Photonics 2:7 (2008) 415-419
Abstract:
The transient nanoscale dynamics of materials on femtosecond to picosecond timescales is of great interest in the study of condensed phase dynamics such as crack formation, phase separation and nucleation, and rapid fluctuations in the liquid state or in biologically relevant environments. The ability to take images in a single shot is the key to studying non-repetitive behaviour mechanisms, a capability that is of great importance in many of these problems. Using coherent diffraction imaging with femtosecond X-ray free-electron-laser pulses we capture time-series snapshots of a solid as it evolves on the ultrafast timescale. Artificial structures imprinted on a Si 3 N 4 window are excited with an optical laser and undergo laser ablation, which is imaged with a spatial resolution of 50nm and a temporal resolution of 10ps. By using the shortest available free-electron-laser wavelengths and proven synchronization methods this technique could be extended to spatial resolutions of a few nanometres and temporal resolutions of a few tens of femtoseconds. This experiment opens the door to a new regime of time-resolved experiments in mesoscopic dynamics. © 2008 Macmillan Publishers Limited. All rights reserved.Optical switching in v O2 films by below-gap excitation
Applied Physics Letters 92:18 (2008)
Abstract:
We study the photoinduced insulator-metal transition in V O2, correlating its threshold and dynamics with excitation wavelength. In single crystals, switching can only be induced with photon energies above the 670 meV gap. This contrasts with the case of polycrystalline films, where formation of the metallic state can be initiated also with photon energies as low as 180 meV, which are well below the bandgap. Perfection of this process may become conducive to schemes for optical switches, limiters, and detectors operating at room temperature in the mid-infrared. © 2008 American Institute of Physics.Enhanced photosusceptibility near Tc for the light-induced insulator-to-metal phase transition in vanadium dioxide (vol 99, art no 226401, 2007)
PHYSICAL REVIEW LETTERS 100:1 (2008) ARTN 019906