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Title: Transient reflectance of photoexcited Cd{sub 3}As{sub 2}

We report ultrafast transient-grating measurements of crystals of the three-dimensional Dirac semimetal cadmium arsenide, Cd{sub 3}As{sub 2}, at both room temperature and 80‚ÄČK. 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 energy and later at lower energy. We attribute their decay to cooling by rapid emission of optical phonons, then slower emission of acoustic phonons. We also present evidence that both the electrons and the lattice are strongly heated.
Authors:
;  [1] ; ;  [2] ; ;  [3]
  1. Department of Physics, Santa Clara University, 500 El Camino Real, Santa Clara, California 95053-0315 (United States)
  2. Institute of Applied Physics, Academy of Sciences of Moldova, Academiei str. 5, MD 2028 Chisinau (Moldova, Republic of)
  3. Departments of Electrical Engineering and Computer Science, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201 (United States)
Publication Date:
OSTI Identifier:
22412552
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 23; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 36 MATERIALS SCIENCE; CADMIUM ARSENIDES; CHARGE CARRIERS; ELECTRONS; EXCITATION; PHASE SPACE; PHASE VELOCITY; PHONONS; PHOTONS; TEMPERATURE RANGE 0273-0400 K; THREE-DIMENSIONAL LATTICES