Hirai Daigorou, Hiroi Zenji
Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
J Phys Condens Matter. 2021 Feb 1;33(13). doi: 10.1088/1361-648X/abda79.
The synthesis and physical properties of the double perovskite (DP) compound BaCdReOwith the 5electronic configuration are reported. Three successive phases originating from a spin-orbit-entangled= 3/2 state, confirmed by a reduced effective magnetic moment of 0.72 , were observed upon cooling. X-ray diffraction measurements revealed a structural transition from a high-temperature cubic structure to a low-temperature tetragonal structure at= 170 K, below which the= 3/2 state was preserved. Magnetization, heat capacity, and thermal expansion measurements showed two more electronic transitions to a possible quadrupole ordered state at= 25 K and an antiferromagnetic order of dipoles with a ferromagnetic moment of ∼0.2 at= 12 K. These properties were compared with those of the DP's sister compounds BaReO(= Mg, Zn, and Ca) and the chemical trend is discussed in terms of the mean-field theory for spin-orbit-coupled 5electrons (2010 Chen174440). The DP BaReOcompounds provide a unique opportunity for a systematic investigation of symmetry breaking in the presence of multipolar degrees of freedom.
报道了具有5电子构型的双钙钛矿（DP）化合物BaCdReO的合成及其物理性质。冷却时观察到三个连续的相，源于自旋轨道纠缠的= 3/2态，有效磁矩降低至0.72证实了这一点。X射线衍射测量表明，在= 170 K时发生从高温立方结构到低温四方结构的结构转变，低于此温度= 3/2态得以保留。磁化、热容量和热膨胀测量表明，在= 25 K时还有另外两个电子跃迁到可能的四极有序态，在= 12 K时偶极子发生反铁磁有序，铁磁矩约为0.2。将这些性质与DP的姊妹化合物BaReO（= Mg、Zn和Ca）的性质进行了比较，并根据自旋轨道耦合5电子的平均场理论（2010年Chen174440）讨论了化学趋势。DP BaReO化合物为在多极自由度存在的情况下系统研究对称性破缺提供了独特的机会。
