Phonon-induced pseudogap phase in TiSe2
Abstract
To comprehend quantum ordered states, such as charge density waves (CDW), in layered transition metal dichalcogenides (TMDCs), it is essential to uncover their underlying normal states. Here, we use time- and angle-resolved extreme ultraviolet photoemission spectroscopy and ab initio electron-phonon calculations to perform excited state band mapping of three prototypical 1T TMDCs, i.e., TiSe2, HfTe2, and ZrTe2, at room temperature. The results reveal the profound impact of strong electron-phonon-induced thermal fluctuations on the normal-phase electronic structure. Specifically, in the moderate electron-phonon coupling regime, as in HfTe2 and ZrTe2, thermal fluctuations only lead to small spectral broadening and band renormalization. In the strongly coupled case, exemplified by TiSe2, we observe soft-phonon-induced, momentum-dependent suppression of spectral weight, i.e., pseudogaps - extending up to 1 eV above the Fermi level. Our work establishes the normal phase of TiSe2 as a phonon-induced pseudogap phase governed by strong CDW fluctuations, thereby uncovering previously missing aspects of the TiSe2 phase diagram, with broader implications for other TMDCs in the strong electron-phonon coupling regime.
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BibTeX
@misc{fragkos2026phononinduced,
title = {{Phonon-induced pseudogap phase in TiSe$_2$}},
author = {Sotirios Fragkos and Nina Girotto Erhardt and Evgenia Symeonidou and Hibiki Orio and Dominique Descamps and Stéphane Petit and Polychronis Tsipas and Kai Rossnagel and Jakub Schusser and Athanasios Dimoulas and Samuel Beaulieu and Dino Novko},
howpublished = {HAL},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2606.31298},
url = {https://hal.science/hal-05778001v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Phonon-induced pseudogap phase in TiSe_2
AU - Sotirios Fragkos
AU - Nina Girotto Erhardt
AU - Evgenia Symeonidou
AU - Hibiki Orio
AU - Dominique Descamps
AU - Stéphane Petit
AU - Polychronis Tsipas
AU - Kai Rossnagel
AU - Jakub Schusser
AU - Athanasios Dimoulas
AU - Samuel Beaulieu
AU - Dino Novko
PY - 2026
DA - 2026/11/05
PB - HAL
DO - 10.48550/arxiv.2606.31298
UR - https://hal.science/hal-05778001v1
AB - To comprehend quantum ordered states, such as charge density waves (CDW), in layered transition metal dichalcogenides (TMDCs), it is essential to uncover their underlying normal states. Here, we use time- and angle-resolved extreme ultraviolet photoemission spectroscopy and ab initio electron-phonon calculations to perform excited state band mapping of three prototypical 1T TMDCs, i.e., TiSe_2, HfTe_2, and ZrTe_2, at room temperature. The results reveal the profound impact of strong electron-phonon-induced thermal fluctuations on the normal-phase electronic structure. Specifically, in the moderate electron-phonon coupling regime, as in HfTe_2 and ZrTe_2, thermal fluctuations only lead to small spectral broadening and band renormalization. In the strongly coupled case, exemplified by TiSe_2, we observe soft-phonon-induced, momentum-dependent suppression of spectral weight, i.e., pseudogaps - extending up to 1 eV above the Fermi level. Our work establishes the normal phase of TiSe_2 as a phonon-induced pseudogap phase governed by strong CDW fluctuations, thereby uncovering previously missing aspects of the TiSe_2 phase diagram, with broader implications for other TMDCs in the strong electron-phonon coupling regime.
ER -