Synthesis and magnetic properties of new tellurate compounds Na4MTeO6 (M = Co and Ni) with a ferromagnetic spin-chain structure

Abstract

New tellurate compounds Na₄MTeO₆ (M = Co and Ni) were synthesized by a conventional high-temperature solid-state reaction. The title compounds crystallize in the monoclinic system of a space group P2/c and the triclinic system of a space group P, respectively. Both compounds exhibit a zigzag spin-chain structure, in which Na₄CoTeO₆ shows uniform chains built by Co²⁺ ions and Na₄NiTeO₆ shows alternating chains built by Ni²⁺ ions. Magnetic measurements confirm that Na₄CoTeO₆ and Na₄NiTeO₆ possess an antiferromagnetic ordering at T_N = ∼3 K and ∼6.5 K, respectively, while a metamagnetic transition can be observed in the magnetization curve with an increasing field at 2 K.