Optical investigation of the charge-density-wave phase transitions in $NbSe_{3}$

TL;DR

This study uses optical reflectivity measurements to analyze the charge-density-wave phase transitions in NbSe3, revealing spectral weight redistribution and partial Fermi surface gapping below transition temperatures.

Contribution

It provides detailed optical data on NbSe3's CDW gaps and discusses the effects of fluctuations and free carrier scattering.

Findings

Spectral weight shifts from low to high energies below CDW transitions.

Partial gapping of the Fermi surface at 145 K and 59 K.

Quantitative estimates of the CDW gap magnitudes.

Abstract

We have measured the optical reflectivity $R(\omega)$ of the quasi one-dimensional conductor $NbSe_{3}$ from the far infrared up to the ultraviolet between 10 and 300 $K$ using light polarized along and normal to the chain axis. We find a depletion of the optical conductivity with decreasing temperature for both polarizations in the mid to far-infrared region. This leads to a redistribution of spectral weight from low to high energies due to partial gapping of the Fermi surface below the charge-density-wave transitions at 145 K and 59 K. We deduce the bulk magnitudes of the CDW gaps and discuss the scattering of ungapped free charge carriers and the role of fluctuations effects.