Momentum-Resolved View of Electron-Phonon Coupling in Multilayer WSe2

L. Waldecker, R. Bertoni, H. Hübener, T. Brumme, T. Vasileiadis, D. Zahn, A. Rubio, and R. Ernstorfer
Phys. Rev. Lett. 119, 036803 – Published 21 July 2017

Abstract

We investigate the interactions of photoexcited carriers with lattice vibrations in thin films of the layered transition metal dichalcogenide (TMDC) WSe2. 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.

  • Figure
  • Figure
  • Figure
  • Figure
  • Received 28 February 2017

DOI:https://doi.org/10.1103/PhysRevLett.119.036803

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

L. Waldecker1,2,*, R. Bertoni1,3, H. Hübener4, T. Brumme4, T. Vasileiadis1, D. Zahn1, A. Rubio4, and R. Ernstorfer1,†

  • 1Fritz Haber Institut of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
  • 2Stanford University, 348 Via Pueblo Mall, Stanford, California 94305, USA
  • 3Univ Rennes 1, CNRS, Institut de Physique de Rennes, UMR 6251, UBL, F-35042 Rennes, France
  • 4Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Notkestrae 85, 22761 Hamburg, Germany

  • *waldecker@stanford.edu
  • ernstorfer@fhi-berlin.mpg.de

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 119, Iss. 3 — 21 July 2017

Reuse & Permissions
Access Options
CHORUS

Article Available via CHORUS

Download Accepted Manuscript
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review Letters

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×