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Transient Reflectance Of Photoexcited Cd3As2, Christopher P. Weber, Ernest Arushanov, Bryan S. Berggren, Tahereh Hosseini, Nikolai Kouklin, Alex Nateprov

Physics

We report ultrafast transient-grating measurements of crystals of the three-dimensional Dirac semimetal cadmium arsenide, Cd₃As₂, at both room temperature and 80 K. After photoexcitation with 1.5-eV photons, charge-carriers relax by two processes, one of duration 500 fs and the other of duration 3.1 ps. By measuring the complex phase of the change in reflectance, we determine that the faster signal corresponds to a decrease in absorption, and the slower signal to a decrease in the light's phase velocity, at the probe energy. We attribute these signals to electrons' filling of phase space, first near the photon …