Quantum Melting of the Charge-Density-Wave State in 1T-TiSe₂

We report a Raman scattering study of low-temperature, pressure-induced melting of the charge-density-wave (CDW) phase of [Formula presented]. Our measurements reveal that the collapse of the CDW state occurs in three stages: (i) For [Formula presented], the pressure dependence of the CDW amplitude mode energies and intensities are indicative of a “crystalline” CDW regime; (ii) for [Formula presented], there is a decrease in the CDW amplitude mode energies and intensities with increasing pressure that suggests a regime in which the CDW softens, and exhibits enhanced fluctuations; and (iii) for [Formula presented], the absence of amplitude modes reveals a metallic regime in which the CDW has melted.