Dirac semimetal phase in the hexagonal LiZnBi

Based on first-principles calculations, we find that LiZnBi, a metallic hexagonal $ABC$ compound, can be driven into a topologically nontrivial Dirac semimetal by strain. The nontrivial topological nature of the strained LiZnBi is directly demonstrated by calculating its $Z_2$ index at $k_z=0$. We show that there are two Dirac points located at the rotation axis, protected by $C_{6v}$ symmetry and time-reversal symmetry. In the calculated surface states, the Fermi arcs connecting the projections of these two Dirac points are found. We also present how the low-energy states as well as topological properties change under different strain configurations. The finding of Dirac semimetal phase in LiZnBi may intrigue further researches on the topological properties of hexagonal $ABC$ materials and promote new practical applications.