Ultrafast momentum-resolved visualization of the interplay between phonon-mediated scattering and plasmons in graphite
| Autor: | Barantani, Francesco, Claude, Rémi, Iyikanat, Fadil, Madan, Ivan, Sapozhnik, Alexey A., Puppin, Michele, Weaver, Bruce, LaGrange, Thomas, de Abajo, F. Javier Garcia, Carbone, Fabrizio |
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| Rok vydání: | 2024 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | Scattering between individual charges and collective modes in materials governs fundamental phenomena such as electrical resistance, energy dissipation, switching between different phases, and ordering. The study of such scattering requires a simultaneous access to the ultrafast momentum-resolved dynamics of single-particle and collective excitations, which remains as an experimental challenge. Here, we demonstrate time- and momentum-resolved electron energy-loss spectroscopy, and apply it to graphite showing that large ($\Delta q\simeq$1.2~{\AA}$^{-1}$) photoexcited electron-hole (e-h) pockets in the band structure induce a renormalization of the collective in-plane and bulk plasmons that can be described quantitatively by invoking intra- and inter-valley scattering processes mediated by $E_{2g}$ and $A_{1}'$ phonon modes, which we directly observe by ultrafast electron diffraction and identify via ab initio calculations. Conversely, the photoexcitation of smaller e-h pockets ($\Delta q\simeq$0.7~{\AA}$^{-1}$) close to the K point of graphite results in the renormalization of in-plane plasmons, which can only be partially explained by phonon-mediated scattering and thermal expansion. Our results show the importance of combining momentum- and time-resolved information to elucidate microscopic details associated with electronic scattering processes. Comment: 16 pages, 4 figures |
| Databáze: | arXiv |
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