Ultrafast dynamics of chiral phonons in WSe₂ by first-principles lattice dynamics simulations

Chiral phonons are unique lattice excitations found in transition metal dichalcogenides (TMDs). They link the valley degree of freedom with optical excitations, giving rise to a range of unconventional physical phenomena, including enhanced exciton recombination and the valley-phonon Hall effect. Since their first observation in WSe₂, chiral phonons have been studied experimentally in several helicity-preserving optical processes. Yet, the ultrafast dynamics of chiral phonons governing such optical excitations is still not completely understood. In this talk, we will present a first-principles study of the coupled dynamics of electrons and chiral phonons in WSe₂, using a method we recently developed based on the solution of the coupled electron and phonon real-time Boltzmann transport equations^[1]. Our preliminary results, discussed in this talk, reveal microscopic details of the ultrafast dynamics of chiral phonons, shedding light on their relaxation and on the link between valley and phonon dynamics in TMDs.