Magnetic Anisotropy of a Triangular Spin-Chain System K2Co3(MoO4)3(OH)2

Low-dimensional magnetic materials have drawn continued attention in condensed matter physics, owing to their distinct electronic and magnetic properties. In particular, the oxyanion-based transition-metal (M) oxide sublattices that are magnetically isolated by closed-shell nonmagnetic oxyanions (MoO₄^2-, SiO₄⁴⁻, PO₄³⁻, AsO₄³⁻) show great potential for exploring and characterizing new emergent phenomena. Recently we have synthesized single crystals of K2Co3(MoO4)3(OH)2 and characterized the crystals structure and magnetic properties. K2Co3(MoO4)3(OH)2 belongs to a rare class of compounds, namely half sawtooth-chain 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 7 K with a strong anisotropy. The isothermal magnetization data shown a stepwise magnetization when the magnetic field along the Co-O-Co (half sawtooth chain) direction. Two noticeable metamagnetic transitions were observed at Hc1 = 1 kOe and Hc2 = 2.1 kOe. The magnetic structure was determined using single crystals neutron diffraction. The magnetic structure consists of ferrimagnetic chains which are antiferromagnetically coupled with each other.