(OH): A Triangular One-Dimensional Chain Structure with a Frustrated Geometry*

Synthesis and characterization of complex competing magnetic interaction systems are a crucial part of the development of theoretical models that can predict the emergent physics in condensed matter systems. 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 CsCo₂(MoO₄)₂(OH) and characterized the crystals structure. CsCo(MoO₄)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 long-range ordering around 5 K with a strong anisotropy. The isothermal magnetization data shown a stepwise magnetization when the magnetic field along the Co-O-Co (saw-tooth chain) direction. Two noticeable metamagnetic transitions were observed at 0.3 kOe and 40 kOe. The magnetic structure consists of ferrimagnetic chains which are antiferromagnetically coupled with each other.