<i>B</i> -Site-Tuned Curie Temperature and Band Gap in Half-Metallic LaCu ₃ <i>B</i> ₂ Re ₂ O ₁₂ ( <i>B</i> = Fe, Co, Ni) Quadruple Perovskite Oxides

An <i>A</i>- and <i>B</i>-site-ordered quadruple perovskite oxide LaCu₃Ni₂Re₂O₁₂ was synthesized at 9 GPa and 1323 K. The crystal structure adopts a cubic space group of <i>Pn</i>-3 with the lattice constant <i>a</i> = 7.4961(1) Å. Bond valence sum calculation and X-ray absorption spectroscopy suggest the charge distribution to be La³⁺Cu²⁺₃Ni²⁺₂Re^5.5+₂O₁₂. A ferrimagnetic transition arising from the Cu²⁺(↑)-Ni²⁺(↑)-Re^5.5+(↓) spin coupling is found to occur at a Curie temperature of <i>T</i>_C ≈ 210 K. First-principles calculations suggest a half-metallic electronic band structure for LaCu₃Ni₂Re₂O₁₂ with an energy gap of about 1.9 eV at the up-spin channel and a conducting band at the down-spin channel. By comparison with other isostructural LaCu₃<i>B</i>₂Re₂O₁₂ (<i>B</i> = Fe, Co, Ni) perovskites, we find that the electronic configuration of Re dominates the Curie temperature, as well as the half-metallic band gap.