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

Abstract

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.