One-dimensional ferromagnetism of gaudefroyite Ca₄(MnO)₃(BO₃)₃CO₃

The structure of gaudefroyite, Ca-4(MnO)(3)(BO3)(3)CO3, is built up of linear chains of edge-shared MnO6 octahedra which are interconnected via BO3 groups to form a Kagome lattice in the ab plane. Magnetic measurements show that the Mn moments along the chain are ferromagnetically coupled, but frustration exists between the chains because of the triangular arrangement of the Mn ions within the ab plane. Over a large temperature range, 10 Kless than or equal toTless than or equal to320 K, the magnetic properties of this compound can be described by the classical Heisenberg spin chain model with a single ion anisotropy modification, H=-2JSigmaS(i)S(i+1)+DSigmaS(iz)(2), with J=4.2 K and D=0.67 K. Below 10 K, the moments are effectively constrained to the ab plane and the magnetization with H(0)parallel toab shows spin glass behavior. No indication of magnetic ordering has been observed down to 1.8 K.