Specific heat and magnetization measurements have been carried out under a range of magnetic fields on single crystals of ${\mathrm{Ca}}_3{\mathrm{Co}}_2{\mathrm{O}}_6.$ This compound is composed of Ising magnetic chains that are arranged on a triangular lattice. The intrachain and interchain couplings are ferromagnetic and antiferromagnetic, respectively. This situation gives rise to geometrical frustration, that bears some similarity to the classical problem of a two-dimensional Ising triangular antiferromagnet. This paper reports on the ordering process at low T and the possibility of one-dimensional features at high T.

• Received 27 February 2003

DOI:https://doi.org/10.1103/PhysRevB.68.014424