Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 28: FS: Time-Resolved Spectroscopy in Correlated Electron Systems:
Experiment and Theory

TT 28.4: Topical Talk

Thursday, March 25, 2010, 10:45–11:15, H18

Time resolved photoemission and THz spectroscopy of high temperature superconductors — •Luca Perfetti — Laboratoire des Solides Irradiés, École Polytechnique, 91128 Palaiseau Cedex, France — Fachbereich Physik, Freie Universitaet, Arnimallee 14, 14195 Berlin, Germany

I will review some of the open questions concerning the mechanism of high temperature superconductivity. Our approach makes use of non-equilibrium techniques in order to disentangle electronic degrees of freedom from lattice modes. The time resolved photoemission technique and time resolved THz spectroscopy will be presented. These experiments provide novel information on the elementary interactions dressing the quasiparticles as well as on the calorimetry of the electrons. The relaxation time of the photoexcited state indicates that the electron-phonon coupling is too weak in order to provide the pairing interaction. Simple considerations based on the energy conservation allow for an extraction of the electronic specific heat over a wide temperature range. These results offer new insights on the phase diagram and the occurrence of a pseudogap in underdoped compounds.