Magnetic properties of Co²⁺ions in octahedral interstices of an oxide lattice

The magnetic properties of Co2+ ions in octahedral environment are discussed in relation to the energy-level scheme. It appears that the three low-lying levels arising from the 4F(Γ4) triplet as a consequence of spinorbit coupling are responsible for a temperature-dependent magnetic moment. The expected departure from the Curie-Weiss law is demonstrated by susceptibility measurements on mixed-crystals of CoO and MgO between 300° and 1200°k. From the experimental data the spin-orbit coupling constant for Co2+ in these compounds is estimated to be -136 cm-1.