Interplay of Charge Density Wave States and Strain at the Surface of CeTe$_{2}$

TL;DR

This study uses STM to reveal unidirectional charge density wave states in CeTe₂, showing how local strain influences CDW formation and coexistence at the surface, providing insights into the fundamental physics of layered tellurides.

Contribution

It provides the first STM observation of unidirectional CDWs in CeTe₂ and links local strain to CDW behavior at the nanoscale, contrasting prior theoretical predictions.

Findings

Detection of unidirectional CDW with q ~ 0.28 a*

Observation of coexisting CDWs near defects

Correlation between local strain and CDW states

Abstract

We use scanning tunneling microscopy (STM) to study charge density wave (CDW) states in the rare-earth di-telluride, CeTe$_{2}$. In contrast to previous experimental and first-principles studies of the rare-earth di-tellurides, our STM measurements surprisingly detect a unidirectional CDW with $\textit{q}$ ~ 0.28 $\textit{a}$*, which is very close to what is found in experimental measurements of the related rare-earth tri-tellurides. Furthermore, in the vicinity of an extended sub-surface defect, we find spatially-separated as well as spatially-coexisting unidirectional CDWs at the surface of CeTe$_{2}$. We quantify the nanoscale strain and its variations induced by this defect, and establish a correlation between local lattice strain and the locally-established CDW states. Our measurements probe the fundamental properties of a weakly-bound two-dimensional Te-sheet, which experimental and theoretical work has previously established as the fundamental component driving much of the essential physics in both the rare-earth di- and tri-telluride compounds.