Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 86: Low-Dimensional Systems: Charge Order

TT 86.1: Talk

Friday, March 24, 2017, 11:15–11:30, HSZ 103

Origin of the negative plasmon dispersion in NbSe₂ and related systems. — •Eric Müller, Martin Knupfer, and Bernd Büchner — IFW-Dresden, P.O.Box 270116, DE-01171 Dresden, Germany

The charge carrier plasmon excitations of 2H-NbSe₂ and related single crystalline systems have been investigated using electron energy-loss spectroscopy. These systems consist of hexagonal layers with weak interlayer van-der- Waals bonding.

We compare two possible routes to explain the observed unusual negativ plasmon dispersion; charge density wave plasmon interaction and band structure effects. Motivated by the orbital character of the plasmon dispersion in alkali metal doped transition metal dichalcogenides, we demonstrate that the separation of the plasmon from the screening contributions of single particle excitations by a Kramers-Kronig analysis reveals a positive (unscreened) plasmon dispersion.