Spontaneous exciton condensation in 1T-TiSe2: a BCS-like approach

TL;DR

This paper provides a detailed theoretical analysis of exciton condensation in 1T-TiSe2 using a BCS-like model, extending previous theories to three dimensions and comparing results with experimental data.

Contribution

It extends the excitonic insulator phase model to three-dimensional anisotropic bands and compares theoretical spectral functions with experimental photoemission data.

Findings

Spectral function calculations match experimental ARPES data.

The extended model captures the anisotropic and 3D nature of the material.

Evidence supports BCS-like exciton condensation in 1T-TiSe2.

Abstract

Recently strong evidence has been found in favor of a BCS-like condensation of excitons in 1\textit{T}-TiSe$_2$. Theoretical photoemission intensity maps have been generated by the spectral function calculated within the excitonic condensate phase model and set against experimental angle-resolved photoemission spectroscopy data. Here, the calculations in the framework of this model are presented in detail. They represent an extension of the original excitonic insulator phase model of J\'erome \textit{et al.} [Phys. Rev. {\bf 158}, 462 (1967)] to three dimensional and anisotropic band dispersions. A detailed analysis of its properties and further comparison with experiment are also discussed