Pressure dependence of the optical properties of the charge-density-wave compound LaTe$_2$

TL;DR

This study investigates how applying pressure affects the optical properties of LaTe$_2$, revealing a decrease in the charge-density-wave gap and an increase in metallic behavior, with implications for understanding electronic interactions under compression.

Contribution

It provides the first detailed analysis of pressure effects on LaTe$_2$'s optical response, highlighting changes in the CDW gap and electronic properties with pressure.

Findings

The CDW gap decreases with pressure.

The Drude weight increases as pressure is applied.

The power-law behavior remains relatively stable under pressure.

Abstract

We report the pressure dependence of the optical response of LaTe$_2$, which is deep in the charge-density-wave (CDW) ground state even at 300 K. The reflectivity spectrum is collected in the mid-infrared spectral range at room temperature and at pressures between 0 and 7 GPa. We extract the energy scale due to the single particle excitation across the CDW gap and the Drude weight. We establish that the gap decreases upon compressing the lattice, while the Drude weight increases. This signals a reduction in the quality of nesting upon applying pressure, therefore inducing a lesser impact of the CDW condensate on the electronic properties of LaTe$_2$. The consequent suppression of the CDW gap leads to a release of additional charge carriers, manifested by the shift of weight from the gap feature into the metallic component of the optical response. On the contrary, the power-law behavior, seen in the optical conductivity at energies above the gap excitation and indicating a weakly interacting limit within the Tomonaga-Luttinger liquid scenario, seems to be only moderately dependent on pressure.