Infrared signature of the charge-density-wave gap in $ZrTe_3$

TL;DR

This study investigates the infrared optical properties of ZrTe3 across its charge-density-wave transition, revealing the temperature dependence of the CDW gap and the influence of fluctuations above the transition temperature.

Contribution

It provides the first detailed optical reflectivity measurements of the CDW gap in ZrTe3, demonstrating its BCS-like temperature dependence and fluctuation effects.

Findings

The CDW gap follows BCS mean-field behavior below T_CDW.

The CDW gap persists above T_CDW, indicating fluctuation effects.

Optical reflectivity measurements effectively probe the CDW gap in ZrTe3.

Abstract

The chain-like $ZrTe_3$ compound undergoes a charge-density-wave (CDW) transition at $T_{CDW}=63$ $K$, most strongly affecting the conductivity perpendicular to the chains. We measure the temperature ($T$) dependence of the optical reflectivity from the far infrared up to the ultraviolet with polarized light. The CDW gap $\Delta(T)$ along the direction perpendicular to the chains is compatible for $T<T_{CDW}$ with the behavior of an order parameter within the mean-field Bardeen-Cooper-Schrieffer (BCS) theory. $\Delta(T)$ also persists well above $T_{CDW}$, which emphasizes the role played by fluctuation effects.