CaPdBi: A Nontrivial Topological Candidate

Abstract

In the framework of density functional theory, a comprehensive investigation of the mechanical, dynamical, and electronic properties of the compounds CaPdX (X= Sb and Bi) is performed. The investigated systems are both mechanically and dynamically stable. These compounds are claimed to be metallic by the electronic structure properties, with intriguing crossing points in the close proximity of the Fermi level. With spin orbit coupling (SOC) included, a gap appears at particular crossing points. The predicted electronic band structure shows that the d-states of Ca and Pd and the p-states of Bi and Sb dominate at the crossing sites. Inversion and time-reversal symmetry, together with the inclusion of SOC, demonstrate that CaPdBi is a Dirac metal. The calculated Z2 invariants for CaPdSb and CaPdBi are 0 and 1, which infer the trivial and non-trivial strong topological nature, respectively. As a whole, the investigated compound has future scope for its fascinating topological features, one amongst which is the presence of low-energy excitons (Dirac points).