Revealing the role of electrons and phonons in the ultrafast recovery of charge density wave correlations in 1$T$-TiSe${}_2$

Abstract

Using time- and angle-resolved photoemission spectroscopy with selective near- and mid-infrared photon excitations, we investigate the femtosecond dynamics of the charge density wave (CDW) phase in 1$T$-TiSe${}_2$, as well as the dynamics of CDW fluctuations at 240 K. In the CDW phase, we observe the coherent oscillation of the CDW amplitude mode. At 240 K, we single out an ultrafast component in the recovery of the CDW correlations, which we explain as the manifestation of electron-hole correlations. Our momentum-resolved study of femtosecond electron dynamics supports a mechanism for the CDW phase resulting from the cooperation between the interband Coulomb interaction, the mechanism of excitonic insulator phase formation, and electron-phonon coupling.

9 pages, 6 figures

References in corpus (4)

• Evidence for an excitonic insulator phase in 1T-TiSe${}_2$
• Semimetal to semimetal charge density wave transition in 1T-TiSe${}_2$
• Spontaneous exciton condensation in 1T-TiSe2: a BCS-like approach
• Fate of the excitonic insulator in the presence of phonons

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