AC-Conductivity of Pinned Charge Density Wave Fluctuations in Quasi One-Dimensional Conductors

TL;DR

This paper develops a theoretical model for the AC conductivity of charge density wave fluctuations in quasi-one-dimensional conductors, highlighting the effects of impurity pinning and phase breaking on optical properties.

Contribution

It introduces a Ginzburg-Landau-Langevin framework that incorporates impurity pinning and phase breaking to explain conductivity features in fluctuating charge density waves.

Findings

Spectral weight shifts to a pinned mode near the pinning frequency.

Impurities enable the amplitude mode to appear in optical response.

Pinning effects influence the infrared conductivity spectrum.

Abstract

Quasi one-dimensional conductors which undergo a Peierls transition to a charge density wave state at a temperature T_P show a region of one-dimensional fluctuations above T_P. The Ginzburg-Landau-Langevin theory for the frequency dependent collective conductivity from conductive fluctuations into the charge density wave state is developed. By inclusion of a phase breaking term the effect of local pinning due to random impurities is simulated. It is found that the spectral weight of unpinned fluctuations is partly redistributed into a pinned mode around a pinning frequency in the far infrared region. In addition, selection rule breaking by the imputities makes the fluctuating amplitude mode visible in the optical response.