Na₃Bi: A Robust Material Offering Dirac Electrons for Device Applications

Abstract

Na₃Bi, a three dimensional (3D) Dirac semimetal, has been studied by use of density functional theory. The computed lattice constants were in agreement with experimental values. Calculation of the electron density of states and band structure revealed substantial spin–orbit coupling in this compound. This spin–orbit coupling, however, has a negligible effect on relaxed atomic positions obtained by use of force minimization. We also computed the pressure variation of the lattice constants of this compound. From the values obtained for the lattice constants at different pressures we calculated the electronic properties at different pressures up to 2 GPa. At ambient pressure the compound is a Dirac semimetal with linear E(k) dispersion in the conduction band around the Dirac point located at ${\hbox{D}}(0, 0,\sim 0.14\frac{2\pi }{c})$, between Γ and A in the Brillouin zone (BZ). With increasing pressure the lattice constants decrease, with a decreasing less than c. The Dirac point is observed at all the pressures studied and the location of the Dirac point shifts toward the Γ point with increasing pressure. The electronic structure of Na₃Bi was found to be robust to the effects of external or chemical pressure.