Excitonic effects in phonons: reshaping the graphene Kohn anomalies and lifetimes
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arXiv
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| Auteurs principaux: | , , , |
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| Format: | Preprint |
| Publié: |
2025
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| _version_ | 1866915345434935296 |
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| author | Guandalini, Alberto Macheda, Francesco Caldarelli, Giovanni Mauri, Francesco |
| author_facet | Guandalini, Alberto Macheda, Francesco Caldarelli, Giovanni Mauri, Francesco |
| contents | We develop an ab initio framework that captures the impact of electron-electron and electron-hole interactions on phonon properties. This enables the inclusion of excitonic effects in the optical phonon dispersions and lifetimes of graphene, both near the center ($Γ$) and at the border (K) of the Brillouin zone, at phonon momenta relevant for Raman scattering and for the onset of the intrinsic electrical resistivity. Near K, we find a phonon red-shift of ~150 $cm^{-1}$ and a 10x enhancement of the group velocity, together with a 5x increase in linewidths due to a 26x increase of the electron-phonon matrix elements. These effects persist for doping $2E_{F} < {\hbar}ω_{ph}$ and are quenched at higher dopings. Near $Γ$, the excitonic effects are minor because of the gauge field nature of the electron-phonon coupling at small phonon momentum. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_13715 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Excitonic effects in phonons: reshaping the graphene Kohn anomalies and lifetimes Guandalini, Alberto Macheda, Francesco Caldarelli, Giovanni Mauri, Francesco Materials Science Mesoscale and Nanoscale Physics We develop an ab initio framework that captures the impact of electron-electron and electron-hole interactions on phonon properties. This enables the inclusion of excitonic effects in the optical phonon dispersions and lifetimes of graphene, both near the center ($Γ$) and at the border (K) of the Brillouin zone, at phonon momenta relevant for Raman scattering and for the onset of the intrinsic electrical resistivity. Near K, we find a phonon red-shift of ~150 $cm^{-1}$ and a 10x enhancement of the group velocity, together with a 5x increase in linewidths due to a 26x increase of the electron-phonon matrix elements. These effects persist for doping $2E_{F} < {\hbar}ω_{ph}$ and are quenched at higher dopings. Near $Γ$, the excitonic effects are minor because of the gauge field nature of the electron-phonon coupling at small phonon momentum. |
| title | Excitonic effects in phonons: reshaping the graphene Kohn anomalies and lifetimes |
| topic | Materials Science Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2504.13715 |