Phonon Dephasing Dynamics in MoS2

Liuyang Sun, Parveen Kumar, Zeyu Liu, Junho Choi, Bin Fang, Sebastian Roesch, Kha Tran, Joshua Casara, Eduardo Priego, Yu Ming Chang, Galan Moody, Kevin L. Silverman, Virginia O. Lorenz, Michael Scheibner, Tengfei Luo, Xiaoqin Li

Research output: Contribution to journalArticlepeer-review

Abstract

A variety of quantum degrees of freedom, e.g., spins, valleys, and localized emitters, in atomically thin van der Waals materials have been proposed for quantum information applications, and they inevitably couple to phonons. Here, we directly measure the intrinsic optical phonon decoherence in monolayer and bulk MoS2 by observing the temporal evolution of the spectral interference of Stokes photons generated by pairs of laser pulses. We find that a prominent optical phonon mode E2g exhibits a room-temperature dephasing time of ∼7 ps in both the monolayer and bulk. This dephasing time extends to ∼20 ps in the bulk crystal at ∼15 K, which is longer than previously thought possible. First-principles calculations suggest that optical phonons decay via two types of three-phonon processes, in which a pair of acoustic phonons with opposite momentum are generated.

Original languageEnglish (US)
Pages (from-to)1434-1439
Number of pages6
JournalNano letters
Volume21
Issue number3
DOIs
StatePublished - Feb 10 2021

Keywords

  • phonon dephasing
  • scattering phase space
  • transient coherent ultrafast phonon spectroscopy
  • transition metal dichalcogenides

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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