Strain Tuning of Charge Density Wave Order in ErTe₃

Utilizing both x-ray diffraction (XRD) and transport techniques we study the ability of anisotropic strain to manipulate the charge density wave (CDW) order in ErTe₃. ErTe₃ belongs to the rare-earth tritelluride family, RTe₃ (R=La-Pr, Sm, Gd-Tm), which are quasi-2D materials comprising nearly-square Te nets that exhibit unidirectional incommensurate CDW states. These materials are a model system to explore open questions regarding CDW formation and its interrelation with superconductivity and possible nematic phase in related materials such as the cuprates.

Although RTe₃ is weakly orthorhombic and the primary CDW forms along the longer in-plane direction, Kohn anomalies are nevertheless observed at equivalent wavevectors in both in-plane directions, suggesting the material is ‘almost tetragonal’. Here, we demonstrate that the material can indeed be biased to an effectively tetragonal state via strain tuning opening a pathway to realizing nematic behavior in a fundamentally orthorhombic material. Present verification of the ability to strain tune the CDW orientation in this material makes it an ideal candidate to host a possible vestigial nematic phase.