Tuning the scattering mechanism in the three-dimensional Dirac semimetal Cd₃As2

Abstract

To probe the charge-scattering mechanism in Cd₃As2 single crystal, we analyzed the temperature and magnetic-field dependence of the Seebeck coefficient (S). The large saturation value of S at high field clearly demonstrates the linear energy dispersion of a three-dimensional Dirac fermion. A wide tunability of the charge-scattering mechanism has been realized by varying the strength of the magnetic field and the carrier density via In doping. With the increase in magnetic field, the scattering time crosses over from being nearly energy independent to a regime of linear dependence. On the other hand, the scattering time enters into the inverse energy-dependent regime and the Fermi surface strongly modifies with 2% In doping at Cd sites. With further increase in In content from 2% to 4%, we did not observe any Shubnikov–de Haas oscillation up to a 9 T field, but the magnetoresistance is found to be quite large as in the case of the undoped sample.