Broadband hot-carrier dynamics in three-dimensional Dirac semimetal Cd3As2

The hot-carrier relaxation dynamics of Cd3As2 thin films has been investigated by using femtosecond pump-probe spectroscopy in a transmission geometry. A comparative study of degenerate and non-degenerate experiments reveals that hot-carrier distribution in Cd3As2 is established with a time constant of ∼400 fs. Significantly, the broadband measurements allow the extraction of the time evolution of electron temperature and the carrier-phonon coupling factor g = 5.3 × 1015 W m−3 K−1 is deduced by a semiclassical two-temperature model. These results provide fundamental insights into the hot-carrier dynamics of Cd3As2.