Effect of Charge Order on the Plasmon Dispersion in Transition-Metal Dichalcogenides

Jasper van Wezel, Roman Schuster, Andreas König, Martin Knupfer, Jeroen van den Brink, Helmuth Berger, Bernd Büchner

Research output: Contribution to journalArticle (Academic Journal)peer-review

49 Citations (Scopus)


We investigate the dispersion of the charge carrier plasmon in the three prototypical charge-density wave bearing transition-metal dichalcogenides 2H-TaSe2, 2H-TaS2 and 2H-NbSe2 employing electron energy-loss spectroscopy. For all three compounds the plasmon dispersion is found to be negative for small momentum transfers. This is in contrast to the generic behavior observed in simple metals as well as the related system 2H-NbS2, which does not exhibit charge order. We present a semiclassical Ginzburg-Landau model which accounts for these observations, and argue that the vicinity to a charge ordered state is thus reflected in the properties of the collective excitations.
Original languageEnglish
Article number176404
Pages (from-to)1-5
Number of pages5
JournalPhysical Review Letters
Issue number17
Publication statusPublished - 18 Oct 2011


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