DFT investigations on the electronic structure, magnetism, thermodynamic and elastic properties of newly predicted cobalt based antiperovskites: Co3XN (X=Pd, Pt & Rh)

Abstract In this report, we have applied the muffin tin orbital method within full-potential linearized augmented plane wave approximation to investigate the intricate details of the electronic structure, elastic properties and magnetism of antiperovskite compounds Co3XN with X = Rh, Pd and Sn. The detailed analysis of the electronic structure calculations using various chemical bonding indicators suggest the covalent hybridization of the electronic states associated with Co (the high valency transition element) and the X atom (low valency transition element) as the significant interaction liable for the exhibition of the octahedral symmetry by these alloys. The large magnetic moments of Co3RhN, Co3PdN and Co3PtN are observed to be 6.20 μB, 5.20 μB and 6.21 μB, respectively; with a net magnetic moment of around 4.7 μB contributed by Co atoms in each compound. The direct exchange between Co and X atoms and indirect interaction between Co and Co via N atoms is responsible for its ferromagnetic character. The influence of the strain on the overall magnetism and relative atomic moments in the unit cell is also investigated. We have shown the anisotropic nature of these alloys and the mechanical properties like ductility increases from Rh>Pd>Pt. Also, the Debye temperatures of Co3RhN, Co3PdN and Co3PtN are calculated to be 702 K, 689 K and 606 K, respectively.