Competing Magnetic Ground States of Novel Sawtooth Co²⁺ <i>S</i> = 3/2 Chains in NaCo₂(SeO₃)₂(OH)

Low-dimensional magnetic materials have drawn continued attention in condensed matter physics, owing to their distinct electronic and magnetic properties. In particular, the oxyanion systems-based transition-metal (M) oxide sublattices that are magnetically isolated by closed-shell nonmagnetic oxyanions (SiO₄⁻⁴, PO₃⁻⁴, AsO₃⁻⁴) show great potential for exploring and characterizing new emergent phenomena. Recently we have synthesized single crystals of NaCo₂(SeO₃)₂(OH) and characterized the crystals structure. NaCo₂(SeO₃)₂(OH) belongs to a rare class of compounds, namely delta-chain or saw tooth type structure in which corner sharing isosceles triangles whose vertices consist of one Co(1) and two Co(2) atoms. The magnetic susceptibility reveals a two competing magnetic transition at T_N1 = 11 K and T_N2 = 3.2 K. The isothermal magnetization data shown a field induced transition at 1.3 kOe. Neutron powder diffraction was used to determine the magnetic structure.