Electronic structure and topological features in RNiSb compounds

RNiSb intermetallic compounds (R = rare earth elements) belong to the RTX (T = 3d/4d/5d transition metals, and X = p elements) family with a variety of properties and phenomena promising for functional applications. In RNiSb with some R, high mobility ratio and high-temperature power factor are found. The intermetallic compounds are crystalized in the MgAgAs-type (space group F-43m) half-Heusler structure. In this work, the electronic structure and magnetic properties of these RNiSb (R = Gd-Er) compounds are investigated in the framework of the DFT+U method based on density functional theory and accounting for strong electron correlations in the 4f shells of the R ions. All compounds are found to be narrow gap semiconductors with the indirect gap in the electronic structure in both spin projections. The band structure exhibits the presence of occupied bands which can form a hole pocket near Γ point (L-ΓX, K-Γ) at the Fermi energy. The occupied bands have the nonsymmetric band near X point (Γ-XW) and another band near K-point at higher energies. The calculated magnetic properties are solely caused by the magnetic moments of the R ions and provide a good agreement with the experimental data. (author)