Magnetic Anisotropy of Ca3Co2O6with Ferromagnetic Ising Chains

Magnetic properties of Ca 3 Co 2 O 6 with ferromagnetic Ising chains have been studied using oriented sample along the chain direction. From the extremely anisotropic behavior in its magnetization at low temperatures and in the temperature dependence of magnetic susceptibility, it is suggested that an octahedral Co 3+ is nonmagnetic, whereas a trigonal prismatic Co 3+ has a fictitious spin S '=1 with large single-ion anisotropy ( D ∼-25 K, g // ∼4). At low temperatures below 5 K, multisteps are observed in the magnetization, suggesting the existence of various magnetic structures. The pulsed magnetization measurements reveal that the response of ferromagnetic chains to the field is slow and varies as a function of temperature and Δ H /Δ t .