# Evidence for an excitonic insulator phase in 1T-TiSe$_{2}$

## TL;DR

This study provides strong experimental and theoretical evidence that 1T-TiSe2 undergoes a transition to an excitonic insulator phase, explaining its charge-density wave behavior through spectral modifications observed in photoemission data.

## Contribution

The paper combines high-resolution photoemission experiments with theoretical spectral function calculations to support the excitonic insulator phase in 1T-TiSe2.

## Key findings

- Large band renormalizations at high-symmetry points
- Spectral weight transfer to backfolded bands
- Good agreement between experiment and excitonic insulator model

## Abstract

We present a new high-resolution angle-resolved photoemission study of 1\textit{T}-TiSe$_{2}$ in both, its room-temperature, normal phase and its low-temperature, charge-density wave phase. At low temperature the photoemission spectra are strongly modified, with large band renormalisations at high-symmetry points of the Brillouin zone and a very large transfer of spectral weight to backfolded bands. A theoretical calculation of the spectral function for an excitonic insulator phase reproduces the experimental features with very good agreement. This gives strong evidence in favour of the excitonic insulator scenario as a driving force for the charge-density wave transition in 1\textit{T}-TiSe$_{2}$.