Andrea Cavalleri

Abstract:

We use sub-10 fs laser pulses in the visible and near IR region of the spectrum in order to probe the dynamics of photo-induced phase transitions on their characteristic timescales. We present results from two different cases: the 1D organic Mott insulator ET-F2TCNQ and the more complex, colossal magneto-resistive manganite, Pr0.7Ca0.3MnO 3. For the former, we find that the melting of the Mott state takes 20 fs, a timescale which is dictated by the electron tunnelling time, h/t. In comparison, the dynamics of the manganite show coupling to a 14 THz structural mode and a high frequency 30 THz mode, which we assign as an orbiton, a collective electronic excitation. © 2009 IOP Publishing Ltd.

Abstract:

The XUV monochromator for ultrashort pulses at the ARTEMIS beamline is presented. It adopts an innovative configuration with gratings in the off-plane mount. The design and characterization of the monochromator are discussed. © 2009 Optical Society of America.

Abstract:

The XUV monochromator for ultrashort pulses at the ARTEMIS beamline is presented. It adopts an innovative configuration with gratings in the off-plane mount. The design and characterization of the monochromator are discussed. © 2009 Optical Society of America.

Abstract:

Ultrafast light pulses can be used to control electronic, magnetic and structural phases of complex solids. Here, we investigate the dynamics of insulator-metal phase transitions in colossal magnetoresistive (CMR) manganites by a combination of femtosecond visible-to-midinfrared pump-probe techniques and transport measurements. We show that an insulator-metal transition can be stimulated in CMR manganites by both above bandgap excitation and selective excitation of individual vibrational degrees of freedom. These two approaches rely on the ultrafast manipulation of parameters controlling the electronic filling and the electronic bandwidth respectively, extending the concepts of filling and bandwidth control to the ultrafast timescale. The ultrafast vibrational control of correlated-electron phases may provide new insights into the role played by lattice vibrations in determining the electronic properties of complex solids. © 2009 IOP Publishing Ltd.