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arXiv · 2104.01833

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

Daigorou Hirai·Zenji Hiroi
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Abstract

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 {\mu}B, 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 {\mu}B 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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Daigorou Hirai, Zenji Hiroi. 2021-04-05. Possible quadrupole order in tetragonal Ba2CdReO6 and chemical trend in the ground states of 5d1 double perovskites. https://doi.org/10.1088/1361-648x/abda79

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