First principles quantum analysis of the structural, electronic, optical, spintronic, and mechanical properties of doped half-Heusler compounds for green energy applications

First-principles computations have been employed to investigate the structural, electronic, magneto-optical, and elastic features of Half-Heusler compounds Ho_1-xZr_xNiSb (x = 12.5%, 25% & 37.5%) by implementing the FP-LAPW technique in the WIEN2K software. The electronic features (DOS and band dispersions) have been explored, considering the tight association between the d/f-states of Ni/Ho/Zr-atoms. The results calculated by GGA + U approximation indicate that Ho_1-xZr_xNiSb (x = 12.5%, 25% & 37.5%) exhibit metallic properties. The \({\varepsilon }_{2}(\omega )\) ${\epsilon }_2(\omega )$ spectra demonstrate that Ho_1-xZr_xNiSb (x = 12.5%, 25% & 37.5%) exhibit substantial photon absorption throughout a wide range of energies (∼1.0 to ∼6.0 eV). These compounds have low reflectivity towards incident photons and reflect around 45% of incident photons throughout the full energy spectrum. Ho_1-xZr_xNiSb (x = 37.5%) exhibit the highest magnetic moment among Ho_1-xZr_xNiSb (x = 12.5%, 25% & 37.5%) due to hybridization of Ho [ \({4f}^{11}\) ${4f}^{11}$ ], Ni [ \({3d}^{8}\) ${3d}^8$ ], and Zr [ \({4d}^{2}\) ${4d}^2$ ] localized orbitals. These materials have great potential as candidates for future spintronic applications. Moreover, it has been observed that these half-Heusler compounds possess mechanical stability as they satisfy the Born stability criterion. The mechanical features of Ho_1-xZr_xNiSb (x = 12.5%, 25% & 37.5%) are analyzed using elastic metrics such as Pugh’s ratio and Young’s modulus. Furthermore, the examination of Pugh’s ratio and Cauchy's pressure reveals that these half-Heusler compounds exhibit a brittle nature.