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Coherent-Phonon-Driven Intervalley Scattering and Rabi Oscillation in Multivalley 2D Materials
Chenyu Wang1,2, Xinbao Liu1,2, Qing Chen1,2
1Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Physical Review Letters
|August 25, 2023
Summary
Ultrafast electron scattering in WSe2 is driven by coherent phonons, enabling K-to-Q intervalley transitions. This study reveals a new method to control scattering rates via phonon amplitude.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Dynamics
Background:
- Understanding electron-phonon couplings is vital for non-equilibrium dynamics.
- Monolayer transition metal dichalcogenides (TSe2) exhibit unique electronic properties.
Purpose of the Study:
- Investigate ultrafast electron and phonon dynamics in monolayer WSe2.
- Elucidate the mechanism of intervalley scattering from K to Q states.
- Explore the role of coherent phonons in electron scattering.
Main Methods:
- Time-resolved theoretical investigation.
- Ab initio dynamic simulations.
- Construction of a two-level model.
Main Results:
- Coherent lattice vibrations (longitudinal acoustic phonon mode [LA(M)]) promote K-to-Q intervalley transitions on a ~400 fs timescale.
- Coherent-phonon-driven intervalley scattering exhibits unconventional steplike behavior.
- Electronic Rabi oscillations are induced by this scattering process.
- Nonadiabatic coupling effects play a critical role.
Conclusions:
- Coherent phonons significantly influence electron scattering dynamics in WSe2.
- A novel strategy to tune intervalley scattering rates by controlling coherent phonon amplitude is proposed.
- This work opens avenues for experimental investigation using light-induced nonlinear phononics.
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