Detailed Structure of a CDW in a Quenched Random Field

TL;DR

This study uses high-resolution x-ray scattering to analyze the complex structure of charge density waves in Ta-doped NbSe_3, revealing two distinct length scales and insights into pinning mechanisms.

Contribution

It identifies a new amplitude coherence length in the phase-phase correlation function of CDWs in Ta-doped NbSe_3.

Findings

Two length scales are needed to describe the phase correlations.

The amplitude coherence length is approximately 34.4 Å.

Phase fluctuations below this length are suppressed.

Abstract

Using high resolution x-ray scattering, we have measured the structure of the Q_1 CDW in Ta-doped NbSe_3. Detailed line shape analysis of the data demonstrates that two length scales are required to describe the phase-phase correlation function. Phase fluctuations with wavelengths less than a new length scale $a$ are suppressed and this $a$ is identified with the amplitude coherence length. We find that xi_a* = 34.4 \pm 10.3 angstroms. Implications for the physical mechanisms responsible for pinning are discussed.