Investigations of mechanical, magnetic and thermoelectric properties of double perovskites Na2IrX6 (X=Cl, Br) for spintronic and energy harvesting applications

In recent years, double perovskites are emerging in the field of thermoelectrics and spintronics because of their unique properties. The present study aims to investigate the structure, mechanical, electronic, and magnetic response of Na₂IrX₆ (X = Cl, Br) double perovskites using density functional theory. The expansion of lattice parameters from 9.74 to 10.33 Å and reduction of bulk modulus from 48.63 to 39.91 GPa with the evolution of −1.57 and −1.41 eV enthalpy of formation is witnessd for Na₂IrCl₆ and Na₂Irbr₆, respectively. In spin up channel, the bandgap value is noticed as 2.8 and 2.2 eV for these compositions. The calculations of the magnetic moment show that these compositions possess the magnetic moment of ≈1 μ_B and most of this is contributed by Ir due to significant exchange splitting in its 5d-orbitals. Their half metallic ferromagnetic nature and suitable thermoelectric properties make them exciting candidates for spintronic, and thermoelectric applications.