  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.
