High-pressure synthesis, crystal structure and magnetic properties of double perovskite oxide Ba_2CuOsO_6

摘要

A new compositional double perovskite oxide Ba_2CuOsO_6 was synthesized under high-pressure (6 GPa) and high-temperature (1500 ℃) conditions. The polycrystalline Ba_2CuOsO_6 was characterized by synchrotron X-ray diffraction, thermogravimetric analysis, and magnetic susceptibility, isothermal magnetization, and specific heat measurements. The oxide crystallizes in a double-perovskite structure with an I4/m space group, in which Os(VI) and Cu(II) are ordered in the perovskite B-site. Ba_2CuOsO_6 is electrically insulating with an activation energy of 0.813(2) eV and shows antiferromagnetic-Iike characteristics at temperatures of ~55 K and ~70K, The results of the first-principle calculation suggested that the spin-orbit interaction of Os(VI) plays a substantial role in the insulating state. The Jahn-Teller distortion of Cu06 octahedra influences the magnetic characteristics with regard to possible two-dimensional magnetic correlations.