Ultrafast carrier and lattice dynamics in the Dirac semimetal NiTe2

The nonequilibrium fermionic quasiparticle responding to bosonic modes is critical to understand the electromagnetic response of different materials. Using ultrafast optical spectroscopy, this work reveals that sudden variation in the Fermi surface topology induces exotic carrier and phonon dynamics via electron-phonon interaction in the type-II Dirac semimetal NiTe${}_{2}$. This provides the feasibility to manipulate the nonequilibrium carrier and lattice responses in a variety of materials with similar electronic structure, and benefits the development of future ultrafast optoelectronic devices.