Observation of A -site antiferromagnetic and B -site ferrimagnetic orderings in the quadruple perovskite oxide Ca Cu 3 Co 2 Re 2 O 12

A quadruple perovskite oxide $\\mathrm{Ca}{\\mathrm{Cu}}_{3}{\\mathrm{Co}}_{2}{\\mathrm{Re}}_{2}{\\mathrm{O}}_{12}$ was synthesized by high-pressure annealing. This compound crystallizes in an $A$- and $B$-site ordered quadruple perovskite structure with space group $Pn\\text{\\ensuremath{-}}3$. The charge combination is determined to be $\\mathrm{Ca}{{\\mathrm{Cu}}^{2+}}_{3}{{\\mathrm{Co}}^{2+}}_{2}{{\\mathrm{Re}}^{6+}}_{2}{\\mathrm{O}}_{12}$ by bond valence sum analysis and x-ray absorption spectroscopy. In contrast to other isostructural $A{\\mathrm{Cu}}_{3}{B}_{2}{B}_{2}^{\\ensuremath{\u0027}}{O}_{12}$ compounds with a single magnetic transition, a long-range antiferromagnetic phase transition originating from the ${A}^{\\ensuremath{\u0027}}$-site ${\\mathrm{Cu}}^{2+}$ sublattice is found to occur at ${T}_{N}\\ensuremath{\\approx}28\\phantom{\\rule{0.16em}{0ex}}\\mathrm{K}$. Subsequently, the spin coupling between the $B$-site ${\\mathrm{Co}}^{2+}$ and ${B}^{\\ensuremath{\u0027}}$-site ${\\mathrm{Re}}^{6+}$ ions contributes to a ferrimagnetic transition around ${T}_{\\mathrm{C}}\\ensuremath{\\approx}20\\phantom{\\rule{0.16em}{0ex}}\\mathrm{K}$. Strong electrical insulating behavior is identified by optical measurement with an energy gap of approximately 3.75 eV. The mechanisms of the spin interactions are discussed in detail.