Doping Dependence of the Plasmon Dispersion in 2H-Tantalum-Diselenide

TL;DR

This study investigates how potassium doping affects the charge carrier plasmon energy and dispersion in 2H-tantalum-diselenide, revealing unusual doping-dependent behavior linked to charge-density wave interactions.

Contribution

It provides new insights into the doping dependence of plasmon dispersion in a CDW-bearing material, highlighting complex interplay between doping, CDW suppression, and plasma resonance.

Findings

Plasmon dispersion changes sign with doping.

Doping causes discontinuous shifts in plasmon behavior.

Complex phenomena like CDW suppression influence plasmon dynamics.

Abstract

Inelastic electron scattering is applied to investigate the impact of potassium intercalation on the charge carrier plasmon energy and dispersion in the charge-density wave (CDW) bearing compound 2H-tantalum-diselenide. We observe an unususal doping dependence of the plasmon dispersion, which even changes sign upon alkali addition. In contrast to the continous energy shift of the plasmon position upon doping at lowest momentum transfer, its dispersion changes in a rather discontinuous manner. We argue that the observed dynamics can only be explained in a picture, where complex phenomena are taken into account including the suppression of the CDW upon doping as well as the interplay of the CDW and the plasma resonance.