Giant Kohn anomaly and the phase transition in charge density wave ZrTe_3

TL;DR

This paper investigates the giant Kohn anomaly in ZrTe_3, revealing its role in the charge density wave phase transition through phonon softening and fluctuation effects, supported by diffuse x-ray scattering analysis.

Contribution

It provides detailed experimental evidence of the Kohn anomaly and its critical behavior near the phase transition in ZrTe_3.

Findings

Identification of a strong Kohn anomaly in ZrTe_3

Observation of phonon mode softening to zero frequency at T_P

Power law scaling of diffuse x-ray scattering intensity

Abstract

A strong Kohn anomaly in ZrTe_3 is identified in the mostly transverse acoustic phonon branch along the modulation vector q_P with polarization along the a* direction. This soft mode freezes to zero frequency at the transition temperature T_P and the temperature dependence of the frequency is strongly affected by fluctuation effects. Diffuse x-ray scattering of the incommensurate superstructure shows a power law scaling of the intensity and the correlation length that is compatible with an order parameter of dimension n = 2.