Pressure dependence of the single particle excitation in the charge-density-wave CeTe$_3$ system

TL;DR

This study investigates how applying pressure affects the optical properties and charge-density-wave gap in CeTe$_3$, revealing gap closure, spectral weight transfer, and high-energy power-law behavior indicative of Tomonaga-Luttinger liquid characteristics.

Contribution

It provides comprehensive pressure-dependent optical data over a broad spectral range, offering new insights into the CDW state and high-energy behavior in CeTe$_3$ and related materials.

Findings

Progressive closing of the CDW gap under pressure

Spectral weight transfer from gap to Drude component

Observation of power-law behavior above the gap

Abstract

We present new data on the pressure dependence at 300 K of the optical reflectivity of CeTe$_3$, which undergoes a charge-density-wave (CDW) phase transition well above room temperature. The collected data cover an unprecedented broad spectral range from the infrared up to the ultraviolet, which allows a robust determination of the gap as well as of the fraction of the Fermi surface affected by the formation of the CDW condensate. Upon compressing the lattice there is a progressive closing of the gap inducing a transfer of spectral weight from the gap feature into the Drude component. At frequencies above the CDW gap we also identify a power-law behavior, consistent with findings along the $R$Te$_3$ series (i.e., chemical pressure) and suggestive of a Tomonaga-Luttinger liquid scenario at high energy scales. This newest set of data is placed in the context of our previous investigations of this class of materials and allows us to revisit important concepts for the physics of CDW state in layered-like two-dimensional systems.