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arXiv 2104.01833cond-mat.str-el
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四元Ba2CdReO6中可能的四极有序和5d 1双钙钛矿基态的化学趋势

Possible quadrupole order in tetragonal Ba2CdReO6 and chemical trend in the ground states of 5d1 double perovskites

Daigorou Hirai, Zenji Hiroi

摘要:

报道了具有5d 1电子组态的双钙钛矿Ba_2CdReO_6的合成和物理性质。在冷却过程中观察到了三个连续的相位,它们起源于自旋-轨道纠缠的Jeff = 3/2态,并通过约化的有效磁矩为0.72 μB得到了证实。X射线衍射测量显示,在Ts = 170 K时,从高温立方结构到低温四方结构的结构转变,低于该温度时,Jeff = 3/2状态被保留。磁化强度、热容量和热膨胀测量表明,在Tq = 25 K时,两个电子跃迁到可能的四极有序态,在Tm = 12 K时,反铁磁有序的偶极子伴随着~ 0.2 μB的铁磁矩。这些性质与姊妹化合物Ba_2BReO_6(B = Mg,Zn,Ca)的性质进行了比较,并根据自旋轨道耦合5d电子的平均场论[G. Chen等人,B82,174440(2010)]。DP化合物Ba 2BReO 6提供了一个独特的机会,在多极自由度的存在下对称性破缺的系统调查。

英文摘要:

The synthesis and physical properties of the double perovskite (DP) compound Ba2CdReO6 with the 5d1 electronic configuration are reported. Three successive phases originating from a spin-orbit-entangled Jeff = 3/2 state, confirmed by the reduced effective magnetic moment of 0.72 μB, 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 Ts = 170 K, below which the Jeff = 3/2 state was preserved. Magnetization, heat capacity, and thermal expansion measurements showed two more electronic transitions to a possible quadrupole ordered state at Tq = 25 K, and an antiferromagnetic order of dipoles accompanied by a ferromagnetic moment of ~ 0.2 μB at Tm = 12 K. These properties were compared with those of the sister compounds Ba2BReO6 (B = Mg, Zn, and Ca) and the chemical trend is discussed in terms of the mean-field theory for spin-orbit-coupled 5d electrons [G. Chen et al., Phys. Rev. B 82, 174440 (2010)]. The DP compound Ba2BReO6 provides a unique opportunity for a systematic investigation on symmetry breaking in the presence of multipolar degrees of freedom.

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