Half-metallicity of novel halide double perovskites K2CuVCl6 and Rb2CuVCl6: application in next-generation spintronic devices

This work reports the determination of structural, electronic, half-metallic and magnetic properties of new double perovskites K₂CuVCl₆ and Rb₂CuVCl₆ using the full-potential linearized augmented plane wave plus local orbitals method incorporated in the WIEN2k code. The calculations performed for this prediction were framed using the density functional theory, and the exchange and correlation potential were described using the generalized gradient approximation of TB-mBJ (Tran–Blaha modified Becke–Johnson). The structural properties confirmed the stable ferromagnetic ground state of the two studied compounds. The equilibrium structural parameters, such as lattice constant (a₀), bulk modulus (B₀), their first pressure derivative (B′) and minimum of the total energy (E₀), were determined for both the compounds. The electronic properties showed that the studied perovskite compounds were completely half-metallic materials. The half-metallic gap (E_HM) values for the compounds were 1.119 eV (for K₂CuVCl₆) and 1.088 eV (for Rb₂CuVCl₆). The exchange-splitting energy (Δ(d)) was found to be large for both the compounds (Δ(d) = 3.482 eV for K₂CuVCl₆ and Δ(d) = 3.380 eV for Rb₂CuVCl₆). The calculated total magnetic moments of the two studied materials indicated major contributions from V atoms and minor contributions from Cu atoms. Owing to p–d hybridization, feeble magnetic moments were exhibited by the non-magnetic K, Rb, Cu and Cl sites, while the atomic magnetic moment of V atoms decreased from its free space charge of 3.00 μ_B.