Plasmon Evolution and Charge-Density Wave Suppression in Potassium Intercalated Tantalum Diselenide

TL;DR

This study explores how potassium intercalation affects charge-density wave formation in 2H-tantalum diselenide, revealing band filling, CDW suppression, and new superstructures through spectroscopy and theoretical analysis.

Contribution

It provides new insights into how potassium intercalation suppresses CDW and alters the electronic structure in 2H-TaSe2, supported by experimental and computational evidence.

Findings

Potassium intercalation reduces plasma frequency indicating conduction band filling.

Charge-density wave superstructures are suppressed upon intercalation.

A new superstructure emerges due to potassium intercalation.

Abstract

We have investigated the influence of potassium intercalation on the formation of the charge-density wave (CDW) instability in 2H-tantalum diselenide by means of Electron Energy-Loss Spectroscopy and density functional theory. Our observations are consistent with a filling of the conduction band as indicated by a substantial decrease of the plasma frequency in experiment and theory. In addition, elastic scattering clearly points to a destruction of the CDW upon intercalation as can be seen by a vanishing of the corresponding superstructures. This is accompanied by a new superstructure, which can be attributed to the intercalated potassium. Based on the behavior of the c-axis upon intercalation we argue in favor of interlayer-sites for the alkali-metal and that the lattice remains in the 2H-modification.