Principal magnetic susceptibilities of MnO and their temperature dependence

The temperature dependence of the principal susceptibilities, χ_∥ and χ_⊥, of MnO are reported in the range of 4.2 to 300 K from the studies in a single crystal from which nonstoichiometries have been removed. A procedure combining selective stress applied along [111] during measurements (to remove T domains), field dependence of the magnetization (to remove S domains), and the measurement of the initial χ is used to determine both χ_∥ and χ_⊥ below TN (117.9 K). A stress {≤}25 bars is sufficient to remove T domains and a critical field Hc2 kOe is determined from the field dependence of the magnetization for →H∥(111) plane. Comparison of the temperature dependence of χ_⊥ in MnO vis-\`a-vis MnF₂ and RbMnF₃ is made, and it is suggested that the observed differences may at least be partly due to the lattice distortion effects in MnO below TN. For χ_∥ in MnO, the data fitted T² variation to about TN3. Further theoretical work is necessary to explain all the observations in MnO.