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Waldecker L, Bertoni R, Hübener H, Brumme T, Vasileiadis T, Zahn D, Rubio A, Ernstorfer R. Momentum-Resolved View of Electron-Phonon Coupling in Multilayer WSe_{2}. Phys Rev Lett 2017; 119:036803. [PMID: 28777602 DOI: 10.1103/physrevlett.119.036803] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Indexed: 05/21/2023]
Abstract
We investigate the interactions of photoexcited carriers with lattice vibrations in thin films of the layered transition metal dichalcogenide (TMDC) WSe_{2}. Employing femtosecond electron diffraction with monocrystalline samples and first-principles density functional theory calculations, we obtain a momentum-resolved picture of the energy transfer from excited electrons to phonons. The measured momentum-dependent phonon population dynamics are compared to first-principles calculations of the phonon linewidth and can be rationalized in terms of electronic phase-space arguments. The relaxation of excited states in the conduction band is dominated by intervalley scattering between Σ valleys and the emission of zone boundary phonons. Transiently, the momentum-dependent electron-phonon coupling leads to a nonthermal phonon distribution, which, on longer time scales, relaxes to a thermal distribution via electron-phonon and phonon-phonon collisions. Our results constitute a basis for monitoring and predicting out of equilibrium electrical and thermal transport properties for nanoscale applications of TMDCs.
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Affiliation(s)
- L Waldecker
- Fritz Haber Institut of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
- Stanford University, 348 Via Pueblo Mall, Stanford, California 94305, USA
| | - R Bertoni
- Fritz Haber Institut of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
- Univ Rennes 1, CNRS, Institut de Physique de Rennes, UMR 6251, UBL, F-35042 Rennes, France
| | - H Hübener
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Notkestrae 85, 22761 Hamburg, Germany
| | - T Brumme
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Notkestrae 85, 22761 Hamburg, Germany
| | - T Vasileiadis
- Fritz Haber Institut of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
| | - D Zahn
- Fritz Haber Institut of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
| | - A Rubio
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Notkestrae 85, 22761 Hamburg, Germany
| | - R Ernstorfer
- Fritz Haber Institut of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
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