Nonequilibrium Lattice Dynamics in Monolayer MoS2

The coupled nonequilibrium dynamics of electrons and phonons in monolayer MoS2 is investigated by combining first-principles calculations of the electron-phonon and phonon-phonon interactions with the time-dependent Boltzmann equation. Strict phase-space constraints in the electron-phonon scattering are found to influence profoundly the decay path of excited electrons and holes, restricting the emission of phonons to crystal momenta close to a few high-symmetry points in the Brillouin zone. As a result of momentum selectivity in the phonon emission, the nonequilibrium lattice dynamics is characterized by the emergence of a highly anisotropic population of phonons in reciprocal space, which persists for up to 10 ps until thermal equilibrium is restored by phonon-phonon scattering. Achieving control of the nonequilibrium dynamics of the lattice may provide unexplored opportunities to selectively enhance the phonon population of two-dimensional crystals and, thereby, transiently tailor electron-phonon interactions over subpicosecond time scales.

Automated summary

The coupled nonequilibrium dynamics of electrons and phonons in monolayer MoS2 are studied, with strict phase-space constraints in electron-phonon scattering significantly influencing the decay path of excited electrons and holes. The momentum selectivity in phonon emission results in highly anisotropic population of phonons in reciprocal space, persisting for up to 10 ps until thermal equilibrium is restored by phonon-phonon scattering. Achieving control of the nonequilibrium dynamics of the lattice may offer unexplored opportunities to selectively enhance the phonon population of two-dimensional crystals and tailor electron-phonon interactions over subpicosecond time scales.