Anomalous electronic energy relaxation and soft phonons in the Dirac semimetal Cd3As2

The authors investigate here the energy and momentum relaxation in the Dirac semimetal Cd₃As₂ using linear and nonlinear terahertz spectroscopy. They find that the temperature dependence of these rates is consistent with quasielastic phonon-electron scattering down to the lowest temperatures measured. These findings highlight how the Dirac semimetal's unique lattice dynamics, including its low thermal conductivity and soft phonons, offers new insights into potential applications of Cd₃As₂ for electronic and optoelectronic devices.