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

TL;DR

This study uses Raman scattering to investigate how pressure induces the melting of the charge density wave in 1T-TiSe2, revealing a three-stage transition process with distinct regimes.

Contribution

It provides a detailed pressure-dependent analysis of the CDW melting process in 1T-TiSe2 using Raman spectroscopy, identifying three distinct regimes of phase transition.

Findings

CDW state collapses in three stages under pressure

Identification of a regime where CDW softens and decouples from the lattice

Complete melting of CDW occurs above 25 kbar

Abstract

We report a Raman scattering study of low-temperature, pressure-induced melting of the CDW phase of 1T-TiSe2. Our Raman scattering measurements reveal that the collapse of the CDW state occurs in three stages: (i) For P<5 kbar, the pressure dependence of the CDW amplitude mode energies and intensities are indicative of a ``crystalline'' CDW regime; (ii) for 5 < P < 25 kbar, 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 may decouple from the lattice; and (iii) for P>25 kbar, the absence of amplitude modes reveals a melted CDW regime.