Thermal dynamics of charge density wave pinning in ZrTe3

TL;DR

This study visualizes how impurity pinning affects the charge density wave in ZrTe3 across temperatures, revealing a transition from weak to strong pinning linked to phase rigidity loss.

Contribution

It provides direct STM observations of impurity pinning evolution in ZrTe3's CDW, highlighting temperature-dependent changes in pinning strength and correlation.

Findings

Weak impurity pinning at low temperatures

Increased impurity correlation above transition

Persistence of short-range modulations above T_CDW

Abstract

Impurity pinning has long been discussed to have a profound effect on the dynamics of an incommensurate charge density wave (CDW), which would otherwise slide through the lattice without resistance. Here we visualize the impurity pinning evolution of the CDW in ZrTe3 using the variable temperature scanning tunneling microscopy (STM). At low temperatures, we observe a quasi-1D incommensurate CDW modulation moderately correlated to the impurity positions, indicating a weak impurity pinning. As we raise the sample temperature, the CDW modulation gets progressively weakened and distorted, while the correlation with the impurities becomes stronger. Above the CDW transition temperature, short-range modulations persist with the phase almost all pinned by impurities. The evolution from weak to strong impurity pinning through the CDW transition can be understood as a result of losing phase rigidity.