Pressure-induced suppression of charge density phases across the entire rare-earth tritellurides by optical spectroscopy

The rare-earth tritellurides (RTe₃) are a distinct class of 2D layered materials that recently gained significant attention due to hosting such quantum collective phenomena as superconductivity or charge density waves (CDWs). Many members of this van der Waals (vdW) family crystals exhibit CDW behavior at room temperature, i.e., RTe₃ compound where R = La, Ce, Pr, Nd, Sm, Gd, and Tb. Here, our systematic studies establish the CDW properties of RTe₃ when the vdW spacing/interaction strength between adjacent RTe₃ layers is engineered under extreme hydrostatic pressures. Using a non-destructive spectroscopy technique, pressure-dependent Raman studies first establish the pressure coefficients of phonon and CDW amplitude modes for a variety of RTe₃ materials, including LaTe₃, CeTe₃, PrTe₃, NdTe₃, SmTe₃, GdTe₃, and TbTe₃. Results further show that the CDW phase is eventually suppressed at high pressures when the interlayer spacing is reduced and interaction strength is increased. Comparison between different RTe₃ materials shows that LaTe₃ with the largest thermodynamic equilibrium interlayer spacing (smallest chemical pressure) exhibits the most stable CDW phases at high pressures. In contrast, CDW phases in late RTe₃ systems with the largest internal chemical pressures are suppressed easily with applied pressure. Overall results provide comprehensive insights into the CDW response of the entire RTe₃ series under extreme pressures, offering an understanding of CDW formation/engineering in a unique class of vdW RTe₃ material systems.