Topological phase transition in half Heusler alloy ScNiBi via chemical alloying

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.