Realization of a Half Metal with a Record-High Curie Temperature in Perovskite Oxides

Half metals, in which one spin channel is conducting while the other is insulating with an energy gap, are theoretically considered to comprise 100% spin-polarized conducting electrons, and thus have promising applications in high-efficiency magnetic sensors, computer memory, magnetic recording, and so on. However, for practical applications, a high Curie temperature combined with a wide spin energy gap and large magnetization is required. Realizing such a high-performance combination is a key challenge. Herein, a novel A- and B-site ordered quadruple perovskite oxide LaCu₃ Fe₂ Re₂ O₁₂ with the charge format of Cu²⁺ /Fe³⁺ /Re^4.5+ is reported. The strong Cu²⁺ (↑)Fe³⁺ (↑)Re^4.5+ (↓) spin interactions lead to a ferrimagnetic Curie temperature as high as 710 K, which is the reported record in perovskite-type half metals thus far. The saturated magnetic moment determined at 300 K is 7.0 μ_B f.u.^-1 and further increases to 8.0 μ_B f.u.^-1 at 2 K. First-principles calculations reveal a half-metallic nature with a spin-down conducting band while a spin-up insulating band with a large energy gap up to 2.27 eV. The currently unprecedented realization of record Curie temperature coupling with the wide energy gap and large moment in LaCu₃ Fe₂ Re₂ O₁₂ opens a way for potential applications in advanced spintronic devices at/above room temperature.