Steplike magnetization in a spin-chain system:Ca3Co2O6

Because of a ferromagnetic in-chain coupling between Co3+ ions at trigonal sites, Co2O6 chains are considered as large rigid spin moments. The antiferromagnetic Ising model on the triangular lattice is applied to describe an interchain ordering. An evolution of metastable states in a sweeping magnetic field is investigated by the single-flip technique. At the first approximation two steps in the magnetization curve and a plateau at 1/3 of the saturation magnetization are found. Four steps in magnetization are determined in high-order approximations in agreement with experimental results.