BaCa₂M₆Te₃O₁₈ (M = Co, Ni): new 1D zigzag spin-chain compounds with a stacked kagomé structure

The arrangement of 1D spin chains on different 2D lattices forms a stacked structure, giving rise to a variety of interesting magnetic behaviors. Herein, we report a successful synthesis of two new compounds, BaCa₂M₆Te₃O₁₈ (M = Co, Ni), with a rare stacked kagomé structure, where the M²⁺ ions form zigzag chains running along the c-axis and are further arranged into a kagomé lattice in the ab plane. Magnetic measurements confirm that BaCa₂Co₆Te₃O₁₈ possesses an antiferromagnetic order at 12 K and field-induced successive spin-flop transitions at 2 K, while BaCa₂Ni₆Te₃O₁₈ shows a short-range magnetic order at ∼50 K, two long-range antiferromagnetic orders at ∼26 K and ∼23 K, and a field-induced spin-flop transition at 2 K. The results indicate that their different magnetic behaviors are due to their different magnetic ions, Co²⁺ and Ni²⁺, although they have similar structural features and spin lattices.