| Summary: | Identifying a strategy for beneficial band-engineering is vital for the optimization of spintronic materials. In this study, we demonstrate the beneficial effects of electron doping on ferromagnetic (FM) half-Heusler AuMnSn _1− _x Te _x (0 ≤ x ≤ 1) using state-of-the-art first-principles methods. By partially substituting the Sn site with a more ionic Te dopant, we predict a FM metal to a FM-half-metallic semiconductor (FM-HMS) transition at Te doping concentration x ∼ 0.125. The FM-HMS is observed to be stable over a wide range of lattice parameters up to a pressure of ∼24.91 GPa. We determined the magnetic phase diagram that shows a phase transition from FM state at low Te concentration dominated by the FM Ruderman-Kittel-Kasuya-Yosida-type exchange to antiferromagnetic state at high Te concentration mediated by the superexchange coupling mechanism. Using the Heisenberg exchange model, we predict a rather high Curie temperature of ${{\rm{T}}}_{{\rm{C}}}\sim 725\,{\rm{K}}$ that increased with increasing pressure. Our results demonstrate a robust scheme for engineering ferromagnetic half-metallicity in the half-Heusler alloy that is promising for spintronic applications.
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