Topological phase transition in half Heusler alloy ScNiBi via chemical alloying

Abstract Topological insulators (TIs) are quantum materials distinguished by an insulating bulk band gap alongside conducting edge or surface states, a phenomenon that has been extensively investigated in several half-Heusler compounds. These alloys emerge as a fertile arena for realizing a spectrum of exotic topological phases, where the inherent tunability of hybridization (through lattice modula- tion), spin–orbit coupling (SOC), and chemical substitution or doping orchestrates a rich landscape of quantum states. In this study, by utilizing first-principles calculations, we have explored the topo- logical phase transition in the half-Heusler system ScNiBi driven by chemical alloying. The pristine structure is found to have a strong TI nature with incorporating SOC, and it has been confirmed by Z 2 invariant calculation and precise analysis of the surface or edge states. A topological phase transition from a TI to a Weyl semi-metallic (WSM) phase has been witnessed by substituting 50% Ni atoms with transition metal atoms. All the studied alloys ScNi 0.5 M 0.5 Bi(Fe, Mn, Cr and V) are found to have non-zero intrinsic anomalous Hall effect, with ScNi 0.5 V 0.5 Bi possessing the highest anomalous Hall conductivity (AHC) of 239 S/cm at the Fermi level. These findings reveal a tailored spectrum of topological phases in the half-Heusler compound ScNiBi driven by chemical alloying, while also outlining a promising path for future theoretical investigations and experimental efforts to harness novel topological states across the wider class of half-Heusler materials.