Dirac and Weyl topological semimetals are remarkable materials, characterized by strong spin-orbit interaction, which provide a platform for realizing the axion electrodynamics and associated novel quantum phenomena such as the quantum anomalous Hall effect and the quantum topological magneto-electric effect. Their robust topological quantum states may be utilized for creating spintronic devices, whose performance is protected against dissipation and decoherence. Despite considerable progress in the theoretical and experimental understanding of these materials, several fundamental issues are still outstanding. Among these, of particular interest is the role played by impurity doping in affecting the materials topological character. It is well known that the stability of a Dirac node in Dirac semimetals depends crucially on the presence of the special crystal symmetries, in addition to the inversion and the time-reversal symmetry. Breaking these symmetries in DSMs by doping is expected to causes a phase transition to other phases. In this work, using first principles density functional theory calculations, combined with a topological analysis, we have investigated the electronic properties of Cd3As2 and Na3Bi Dirac semimetals doped with non-magnetic and magnetic impurities. Specifically, our work shows that different realizations of doping and strain in the system lead to different topological phases, including the possibility of a peculiar mixed Dirac and Weyl phase in Cd3As2.
2 Mar 2020
arXiv preprint arXiv:2003.01231