Observation of A -site antiferromagnetic and B -site ferrimagnetic orderings in the quadruple perovskite oxide CaCu3Co2

Abstract

A quadruple perovskite oxide CaCu 3 Co 2 Re 2 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-3. The charge combination is determined to be CaCu 2+3 Co 2+ 2 Re 6+ 2 O 12 by bond valence sum analysis and x-ray absorption spectroscopy. In contrast to other isostructural ACu 3 B 2 B 2 O 12 compounds with a single magnetic transition, a long-range antiferromagnetic phase transition originating from the A -site Cu 2+ sublattice is found to occur at T N ≈ 28 K. Subsequently, the spin coupling between the B-site Co 2+ and B -site Re 6+ ions contributes to a ferrimagnetic transition around T C ≈ 20 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.

Research progress on quadruple perovskite oxides

“…The Curie temperature of the 1322-type perovskite CCFOO is significantly enhanced from 320 K to 580 K. 70 Similarly, in 1322-type perovskite CaCu 3 Co 2 Re 2 O 12 , as the temperature decreases, CaCu 3 Co 2 Re 2 O 12 first exhibits long-range AFM order formed by Cu 2+ ions at the A′-site at around 28 K, followed by long-range FM order formed by Co 2+ and Re 6+ in the B and B′ sites at around 20 K. In addition, CaCu 3 Co 2 Re 2 O 12 also exhibits strong insulating properties, and its optical band gap is approximately 3.75 eV, as determined by deep ultraviolet diffuse reflectance spectroscopy. 79…”

Emergent physical properties of perovskite-type oxides prepared under high pressure

“…Similarly, the A-site cation controlled electronic and magnetic properties are also observed in ACu 3 Co 2 Re 2 O 12 (A = Ca and La). 70,71 CaCu 3 Co 2 Re 2 O 12 possesses a charge combination of Cu 2+ /Co 2+ /Re 6+ . It shows an insulating behavior with a large energy gap up to 3.75 eV.…”