Charge Density Waves in Exfoliated Thin Films of Van der Waals Materials

TL;DR

This study investigates how reducing the thickness of titanium diselenide films enhances their charge-density-wave transition temperature, potentially enabling room-temperature applications in quantum information processing.

Contribution

It demonstrates that exfoliated thin films of titanium diselenide exhibit increased charge-density-wave transition temperatures up to ~240 K, surpassing bulk values.

Findings

Transition temperature increases with decreasing film thickness.

Raman spectra modifications indicate the phase transition.

Potential for room-temperature quantum applications.

Abstract

A number of the charge-density-wave materials reveal a transition to the macroscopic quantum state around 200 K. We used graphene-like mechanical exfoliation of titanium diselenide crystals to prepare a set of films with different thicknesses. The transition temperature to the charge-density-wave state was determined via modification of Raman spectra of titanium diselenide films. It was established that the transition temperature can increase from its bulk value to ~240 K as the thickness of the van-der-Waals films reduces to the nanometer range. The obtained results are important for the proposed applications of such materials in the collective-state information processing, which require room-temperature operation.