A half-metallic A- and B-site-ordered quadruple perovskite oxide CaCu₃Fe₂Re₂O₁₂ with large magnetization and a high transition temperature

Strong correlation between spins and conduction electrons is key in spintronic materials and devices. A few ferro- or ferrimagnetic transition metal oxides such as La 1-x Sr x MnO 3, Fe 3 O 4, CrO 2 and Sr 2 FeMoO 6 have spin-polarized conduction electrons at room temperature, but it is difficult to find other spin-polarized oxides with high Curie temperatures (well above room temperature) and large magnetizations for spintronics applications. Here we show that an A- and B-site-ordered quadruple perovskite oxide, CaCu 3 Fe 2 Re 2 O 12, has spin-polarized conduction electrons and is ferrimagnetic up to 560 K. The couplings between the three magnetic cations lead to the high Curie temperature, a large saturation magnetization of 8.7a μ B and a half-metallic electronic structure, in which only minority-spin bands cross the Fermi level, producing highly spin-polarized conduction electrons. Spin polarization is confirmed by an observed low-field magnetoresistance effect in a polycrystalline sample. Optimization of CaCu 3 Fe 2 Re 2 O 12 and related quadruple perovskite phases is expected to produce a new family of useful spintronic materials.</p