LaZn_1−<i>x</i>Bi₂ as a Candidate for Dirac Nodal-Line Intermetallic Systems

Abstract

The complex theoretical analysis of the density of states, band structures, and Fermi surfaces, based on predictions of the density functional theory methods, unveils the unique electronic properties of the LaZn1−xBi2 system. In this paper, the Zn vacancies (for x=0.5) were modeled using a modified unit cell of lower symmetry than that for a fully stoichiometric one (for x=0). The existence of several Dirac-like features in the electronic band structures was found. Some of them were found to be intimately associated with the nonsymmorphic symmetry of the system, and these were investigated in detail. The calculated Fermi surface shapes, as well as the Fermi velocity values (up to ∼1.2 ×106 m/s), are in good agreement with other analogous square-net Dirac semimetals. The combination of charge-carrier uncompensation, relatively small band splitting, and the tolerance factor for square-net semimetals t≤0.95 for LaZn0.5Bi2, constitutes a very promising indicator of the topological features of this system, warranting further experimental studies.

Keywords

• electronic structure
• DFT calculations
• Dirac materials
• structural disorder