High Pressure Synthesization And Physical Property Of High Temperature Ferrimagnetic Perovskite

ABO₃ perovskite oxide has abundant physical properties, and it has became a research hotspot in the interdiscipline of physics, chemistry, and materials science. For the simple ABO₃ perovskite, there has been special chemical doping and preparation method available to develop a variety of complex order perovskite. For example, the so-called B-site order perovskite A₂BB’O₆ structure, which is the octahedron position contains two kinds of suitable B and B’ orderly distribution of ions and atoms in different position. In the B-site ordered perovskite, while the 3/4 A-site ion is replaced by transition metal ions A’, formed both A and B-site ordered perovskite AA’₃B₂B’₂O₁₂. In the AA’₃B₂B’₂O₁₂ perovskite, A’, B and B’ three kinds of magnetic ion coupling and compete, result of A variety of novel physical property. Especially, when the strong correlation 3d electron in the B-site and the B’-site 4d and 5d that with more itinerant-electron interaction, the type of order perovskite structure provide more probability for the design of the multi-functional material. Recently, we synthesized the newly quadruple perovskite CaCu₃Fe₂Os₂O₁₂ and CaCu₃Cr2Os₂O₁₂ which the B and B’-site with the 3d and 5d ion by the high temperature and high pressure means. Then, we tested and analyzed the physical property by XRD, PPMS, VSM, XMCD experiment methods. The result shows that the CaCu₃Fe₂Os₂O₁₂ hold a ferrimagnetic transition temperature as high as 580 K. The saturation magnetization about 5.0 μB/f.u at 2 K, and combining with the XMCD measurement, we estimate the Cu²⁺（↑）Fe³⁺（↑）Os⁵⁺（↓） ferrimagnetic spin coupling. And the electrical transport test exhibit the insulator electric property, what more, the photocurrent measurement and the theoretical calculation proved the about 1 eV energy gap insulator. In the other CaCu₃Cr₂Os₂O₁₂ materials, the ferrimagnetic Curie-Weiss temperature is about 420 K. The saturation magnetization is about 3 μB/f.u. at 2 K, show the analogous spin arrangement with Cu²⁺（↑）Cr³⁺（↑）Os⁵⁺（↓）. But the electrical transport properties measurement demonstrate the narrow bandgap semiconductor. Therefore, we study the ferrimagnetic insulator or semiconductor as the kinds of rare material system, may have potential applications in the future spintronic.