Susceptibility-Derived Sublattice Magnetization in Antiferromagnets

A technique for deriving the sublattice magnetization in antiferromagnets from parallel-magnetic-susceptibility measurements is proposed. The relation between these quantities is derived by means of a molecular-field formalism. However, it is pointed out that the results should have a greater range of validity than the molecular-field theory itself. The theory is applied to the antiferromagnets Mn${\mathrm{F}}_2$, Cu${\mathrm{Cl}}_2$·2${\mathrm{H}}_2$O, and Fe${\mathrm{F}}_2$, and the results are compared to those available for these materials from nuclear-magnetic-resonance and Mössbauer-effect measurements as well as the usual molecular-field results. It is found that the susceptibility-derived results are in excellent agreement with those obtained by direct measurements. A reduction of an order of magnitude in the error between calculated and observed magnetization curves is obtained by using the susceptibility-derived results instead of the usual molecular-field results.