Dynamical Phonon Anharmonicity Drives Charge-Density-Wave Softening and Electronic Quasiparticle Decoherence in Monolayer 1H-NbSe2
Abstract
Charge-density-wave (CDW) instabilities in two-dimensional materials are governed by strongly anharmonic soft phonons, whose dynamical behavior remains poorly understood beyond the statically renormalized vibrations. Here, using monolayer 1H-NbSe2, we investigate how frequency-dependent three- and four-phonon interactions reshape phonon spectral functions and influence electronic excitations. We find that three-phonon interactions induce substantial dynamical softening of CDW modes, increasing the estimated transition temperature relative to static self-consistent phonon theory. Four-phonon interactions further promote such dynamical softening and enhance spectral broadening, producing non-Lorentzian lineshapes that challenge the quasiparticle picture. Incorporating dynamically renormalized phonon frequencies and electron-phonon coupling into Fan-Migdal electron self-energy calculations reveals enhanced electronic kinks, satellite features, and momentum-dependent quasiparticle decoherence, driven by the strong momentum dependence of the electron-phonon coupling matrix elements. These findings establish dynamical anharmonicity as a critical link between soft-mode lattice fluctuations and electronic spectral signatures, providing insights into coupled lattice-electron dynamics in two-dimensional quantum materials.
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BibTeX
@misc{xia2026dynamical,
title = {{Dynamical Phonon Anharmonicity Drives Charge-Density-Wave Softening and Electronic Quasiparticle Decoherence in Monolayer 1H-NbSe2}},
author = {Yi Xia},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.04038},
eprint = {2611.04038},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.04038},
}
RIS
TY - UNPB
TI - Dynamical Phonon Anharmonicity Drives Charge-Density-Wave Softening and Electronic Quasiparticle Decoherence in Monolayer 1H-NbSe2
AU - Yi Xia
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.04038
UR - https://arxiv.org/abs/2611.04038
AB - Charge-density-wave (CDW) instabilities in two-dimensional materials are governed by strongly anharmonic soft phonons, whose dynamical behavior remains poorly understood beyond the statically renormalized vibrations. Here, using monolayer 1H-NbSe2, we investigate how frequency-dependent three- and four-phonon interactions reshape phonon spectral functions and influence electronic excitations. We find that three-phonon interactions induce substantial dynamical softening of CDW modes, increasing the estimated transition temperature relative to static self-consistent phonon theory. Four-phonon interactions further promote such dynamical softening and enhance spectral broadening, producing non-Lorentzian lineshapes that challenge the quasiparticle picture. Incorporating dynamically renormalized phonon frequencies and electron-phonon coupling into Fan-Migdal electron self-energy calculations reveals enhanced electronic kinks, satellite features, and momentum-dependent quasiparticle decoherence, driven by the strong momentum dependence of the electron-phonon coupling matrix elements. These findings establish dynamical anharmonicity as a critical link between soft-mode lattice fluctuations and electronic spectral signatures, providing insights into coupled lattice-electron dynamics in two-dimensional quantum materials.
ER -