Nonequilibrium Charge-Density-Wave Melting in 1 T -TaS 2 Triggered by Electronic Excitation: A Real-Time Time-Dependent Density Functional Theory Study.

Ultrafast charge transfer in van der Waals (vdW) heterostructures enables efficient control of two-dimensional material properties through strong optical absorption and subsequent carrier transfer. Here, using real-time time-dependent density functional theory coupled to molecular dynamics, we investigated the nonequilibrium dynamics of charge-density-wave (CDW) melting in 1 T -TaS 2 triggered by ultrafast charge transfer in 1 T -TaS 2 /MoSe 2 or WSe 2 heterostructures. Despite the fast and sufficient charge transfer from the MoSe 2 (or WSe 2 ) "electrode" to the 1 T -TaS 2 layer, the electronic excitation of the vdW heterostructure does not lead to the nonthermal CDW transition of 1 T -TaS 2 . Instead, the TaS 2 lattice is heated by carrier-lattice scattering, leading to thermal CDW melting at high ionic temperatures. The lack of nonthermal melting follows from the fact that the time scale of carrier recombination in 1 T -TaS 2 is similar to or faster than that of charge transfer. These findings provide physical insights into understanding the CDW melting dynamics in vdW heterostructures under nonequilibrium conditions.