LaHg ₃ Mn ₄ O ₁₂ : An A-Site Nonmagnetic Quadruple Perovskite Oxide with Enhanced Half-Metallic Performances

An A-site-ordered AA'₃B₄O₁₂-type quadruple perovskite oxide LaHg₃Mn₄O₁₂ was prepared by using high-pressure and high-temperature methods. The compound crystallizes in cubic Im3̅ symmetry with a lattice parameter a = 7.5949(2) Å. The introduction of Hg²⁺ at the A' site leads to a significant increase in the Mn-O-Mn bond angle, up to 159.5°. A ferromagnetic phase transition is found to occur at the Curie temperature: TC ≈ 280 K, accompanied by a large saturation magnetic moment of 13.0 μB/f.u. A corresponding anomaly in the electrical resistivity is observed near TC. First-principles calculations reveal a half-metallic electronic band structure with a wide minority-spin energy gap of ∼2.0 eV, while the majority-spin states contribute to metallic electrical transport. The current sample, LaHg₃Mn₄O₁₂ thus provides the first example of A'-site nonmagnetic quadruple perovskite oxide with half-metallic behavior. Moreover, compared with other isostructural RCu₃Mn₄O₁₂ (R = rare earth and Bi) half-metals with magnetic Cu²⁺ at the A' site, LaHg₃Mn₄O₁₂ exhibits significant enhancement in both the minority-spin energy gap and saturation magnetization, making it promising for potential spintronic applications.