Magnetic properties of hydroxy Co-Mica intercalation

The magnetic properties of hydroxy Co-mica intercalation complexes in which Co forms a two-dimensional lattice between mica layers have been investigated. The concentration of Co was varied up to 22 wt%. Ferromagnetism with the easy axis of magnetization in the ab-plane (layer plane) appears above about 5 wt%. The Curie temperature shows only a slight increase from about 7 to 8 K with increasing x up to 22.4 wt%. The magnetic moment m at 4.2 K measured in magnetic fields up to 80 kOe is about 2.3μ_B (P_eff = 3.8μ_B), while P_eff at high temperatures obtained by the Curie constant is about 5.3μ_B. These magnetic properties are explained by the features of Co²⁺ ions surrounded by an octahedral crystal and by a formation of Co²⁺ clusters in the 2-dimensional lattice between mica layers.