Formation and magnetic properties of spark plasma sintered Mn_3−δGa (δ = 0, 1) Heusler alloys: Experiment and theory

In this study, we synthesized D0₂₂ Mn_3−δGa (δ = 0, 1) alloys using the spark plasma sintering method. The m(T) results confirmed the formation of the D0₂₂ phase with T_c ≃ 780 K (710 K) for Mn₃Ga (Mn₂Ga). The alloys exhibited hard magnetic behavior with large room temperature spontaneous magnetization of m_s(80 kOe) = 1.63 (0.83) μ_B/f.u. and coercivity of H_c = 4.28 (3.35) kOe for Mn₃Ga (Mn₂Ga). The magnetic properties were investigated further up to T_c and H_c (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.