Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 48: Surface dynamics I
O 48.1: Vortrag
Mittwoch, 24. März 2010, 10:30–10:45, H40
Probing the Momentum-Dependent Response of the Charge Density Wave Phase in TbTe3 by Ultrafast Time- and Angle-Resolved Photoemission — •P.S. Kirchmann1,2, F.T. Schmitt1, U. Bovensiepen2,3, R.G. Moore1, L. Rettig2, M. Krenz2, J.-H. Chu1, N. Ru1, L. Perfetti2,4, M. Wolf2,5, I.R. Fisher1, and Z.-X. Shen1 — 1Department of Applied Physics, Stanford University, Stanford, CA 94305, USA — 2Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany — 3Universität Duisburg-Essen, Institut für Experimentelle Physik, 47048 Duisburg, Germany — 4Ecole Polytechnique, 91128 Palaiseau cedex, France — 5Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany
Charge density wave (CDW) systems such as TbTe3 offer fascinating options for studying the correlation of electrons and the lattice. We investigate the ultrafast response of the charge density wave (CDW) phase in TbTe3 [1] after femtosecond IR excitation using time- and angle-resolved photoemission [2]. The time-dependent photoemission intensity at the Fermi level yields a characteristic time for the closing of the CDW bandgap. With increasing laser fluence the bandgap closes faster, pointing to an increasing slope of the excited potential energy surface. As function of electron momentum the amplitude of the response increases strongly at the position of the Fermi wave vector kF. These results vividly demonstrate that the CDW system is most susceptible to electronic excitations near kF and that these electronic perturbations drive collective excitations of the coupled electron-lattice system. [1] Phys. Rev. B 77 (2008) 235104. [2] Science 321 (2008) 1649.