Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 11: CE: Low-dimensional Systems - Materials 2
TT 11.1: Vortrag
Dienstag, 23. März 2010, 09:30–09:45, H18
Electron Energy-Loss Spectroscopy on the Transition-Metal Dichalchogenide 2H-TaSe2 — •Andreas König1, Roman Schuster1, Helmuth Berger2, Martin Knupfer1, and Bernd Büchner1 — 1Institute for Solid State Research, IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany — 2Insitut de Physique de la Matière Complexe, EPFL, CH-1051 Lausanne, Switzerland
2H-TaSe2 is one of the various polytypes of the transition-metal dichalchogenide (TMDC) TaSe2. It consists of hexagonal layers with weak interlayer van-der-Waals bonding. It shows phase transitions to a charge-density wave (CDW) and to a superconducting state. Although there is strong evidence for the competition of these two ordering effects as well as for a Peierls transition scenario for the origin of the CDW, a theoretical understanding of the mechanism leading to the phase transitions is still subject of discussions. What is already proved for 2H-TaSe2 and a few other TMDCs is a negative dispersion of the bulk plasmon in the normal state and an even larger bandwidth of this negative dispersion in the CDW state, which is altogether not a common metal behavior [1]. We performed Electron Energy-Loss Spectroscopy in transmission on thin films of 2H-TaSe2 for different temperatures above and below the CDW transition temperature to investigate the connection of the CDW phase transition to the plasmon dispersion.
[1] Schuster et al., Phys. Rev. B. 79, 045134 (2009)