Formation and magnetic properties of spark plasma sintered Mn3−δGa (δ = 0, 1) Heusler alloys: Experiment and theory

Abstract In this study, we synthesized D022 Mn3−δGa (δ = 0, 1) alloys using the spark plasma sintering method. The m(T) results confirmed the formation of the D022 phase with Tc ≃ 780 K (710 K) for Mn3Ga (Mn2Ga). The alloys exhibited hard magnetic behavior with large room temperature spontaneous magnetization of ms(80 kOe) = 1.63 (0.83) μ B /f.u. and coercivity of Hc = 4.28 (3.35) kOe for Mn3Ga (Mn2Ga). The magnetic properties were investigated further up to Tc and Hc (T) analysis using the Stoner–Wohlfarth model demonstrated the nucleation mechanism for the magnetization reversal. Calculations of the electronic density of states confirmed the magnetic contribution from two symmetrically inequivalent Mn sites in a Heusler-like tetragonal phase. Density functional theory calculations also showed that the ground state of D022 Mn2Ga was achieved by the removal of Mn atoms from the full Heusler Mn3Ga structure in accordance with the half-Heusler alloy structure, which supported the experimental observations.