Electronic, structural and optical properties of rare-earth based TbNiSb half Heusler compound

Abstract

Half-Heusler (HH) compounds have potential applications in many fields including spintronics and future energy applications. Rare earth based Heusler materials are best suitable for thermoelectric materials. To calculate some physical properties (the electronic, optical-properties) of rare earth (RE) based ternary HH TbNiSb compound, we applied full potential linearized augmented plane wave (FPLAPW) method which is based on Density Functional Theory (DFT). We use the Coulomb corrected generalized gradient approximation (GGA+U) for this study. The calculation of total density of states (DOS) of TbNiSb shows that Ni-3d states dominate in valence band (VB) around -2 eV below fermi energy level (EF) in both spin-up and spin-down configurations, while spin up Tb-5d & spin down Tb- 4f states constitute the conduction band (CB) around 4 eV above the EF. We found a narrow energy gap 0.115 eV is opened showing the semiconducting nature of the TbNiSb compound. Tb –4f states lie around -8 eV below EF and not participate to the DOS near EF. We have also calculated the optical properties like dielectric constant, extinction coefficient, refractive index and reflectivity of TbNiSb compound.