Effect of disorder on the strain-tuned charge density wave multicriticality in Pd$_x$ErTe$_3$

TL;DR

This study investigates how disorder introduced by Pd intercalation affects the strain-tuned charge density wave and multicriticality in ErTe₃, revealing that disorder shifts critical points and influences electronic nematic responses.

Contribution

It demonstrates that disorder modifies the phase transition behavior and nematic response in PdₓErTe₃, providing new insights into disorder effects on charge density waves and criticality.

Findings

Disorder broadens CDW transition signatures but preserves the first-order transition line.

The critical point shifts to lower temperature and strain with disorder.

Disorder enhances the pseudo-tetragonal electronic response despite structural orthorhombicity.

Abstract

We explore, through a combination of x-ray diffraction and elastoresistivity measurements, the effect of disorder on the strain-tuned charge density wave and associated multicriticality in Pd$_x$ErTe$_3$ (x = 0, 0.01, 0.02 and 0.026). We focus particularly on the behavior near the strain-tuned bicritical point that occurs in pristine ErTe$_3$ (x=0). Our study reveals that while Pd intercalation somewhat broadens the signatures of the CDW phase transitions, the line of first-order transitions at which the CDW reorients as a function of applied strain persists in the presence of disorder and still seemingly terminates at a critical point. The critical point occurs at a lower temperature and a lower strain compared to pristine ErTe$_3$. Similarly, the nematic elastoresistance of Pd$_x$ErTe$_3$, though suppressed in magnitude and broadened relative to that of ErTe$_3$, has a markedly more symmetric response around the critical point. These observations point to disorder driving a reduction in the system's electronic orthorhombicity even while the material remains irrevocably orthorhombic due to the presence of a glide plane in the crystal structure. Disorder, it would appear, reinforces the emergence of a "pseudo-tetragonal" electronic response in this fundamentally orthorhombic material.