Investigation of the half-metallic properties of cubic perovskites RCoO3 (R=Pr and Nd): A DFT perspective

Abstract

The structural, electronic, and magnetic properties of cubic perovskite compounds RCoO₃ (R = Pr and Nd) are studied using the full-potential linearized augmented plane wave (FPLAPW) method based on density functional theory (DFT). The phonon dispersion curves, elastic properties and formation energies confirm the stability of both perovskites. The analysis is performed using two exchange-correlation (XC) functionals: GGA and mBJ-GGA. Among these, the semi-local mBJ-GGA potential predicts half-metallic band gaps of 0.40 eV for PrCoO₃ and 0.37 eV for NdCoO₃, indicating that both compounds exhibit half-metallicity. The elastic constants C₁₁, C₁₂, and C₄₄ for the cubic perovskites are calculated to assess the dynamical stability of the materials and are subsequently used to determine elastic moduli—namely, the shear modulus, Young’s modulus, and bulk modulus. Additional mechanical properties, including Poisson’s ratio, anisotropy factor, and Pugh’s ratio, are also evaluated. The total magnetic moment is primarily attributed to the rare-earth (R) atom, while small induced magnetic moments are observed on the Co and O atoms. The half-metallic nature of the compounds is confirmed by the integer values of total magnetic moments i.e. 2 μ_B for PrCoO₃ and 3 μ_B for NdCoO₃. The presence of a half-metallic gap and 100 % spin polarization at the Fermi level (E_F) demonstrates that these compounds are true half-metallic ferromagnets and may be suitable for spintronic applications.