Structural contributions to the pressure-tuned charge-density-wave to superconductor transition in ZrTe3: Raman scattering studies

Superconductivity evolves as functions of pressure or doping from charge-ordered phases in a variety of strongly correlated systems, suggesting that there may be universal characteristics associated with the competition between superconductivity and charge order in these materials. We present an inelastic light (Raman) scattering study of the structural changes that precede the pressure-tuned charge-density-wave (CDW) to superconductor transition in one such system, ZrTe3. In certain phonon bands, we observe dramatic linewidth reductions that accompany CDW formation, indicating that these phonons couple strongly to the electronic degrees of freedom associated with the CDW. The same phonon bands, which represent internal vibrations of ZrTe3 prismatic rods, are suppressed at pressures above similar to 10 kbar, indicating a loss of long-range order within the rods, specifically amongst intrarod Zr-Te bonds. These results suggest that the pressure-induced suppression of CDW order observed in ZrTe3 is structurally driven and provide insights into the origin of pressure-induced superconductivity in this material.