Dipolar interactions in quadratic-layer Heisenberg antiferromagnets have been treated in the spin-wave approximation to calculate the temperature dependence of the sublattice magnetization and the magnon energy gap. Magnon-magnon interactions are included to first order. Numerical results for ${\mathrm{K}}_2$${\mathrm{MnF}}_4$ and the double-layer ${\mathrm{K}}_3$${\mathrm{Mn}}_2$${\mathrm{F}}_7$ confirm the earlier spin-wave analyses of these structures, in which the $k=0\mathrm{}$ magnon energies were made dependent on temperature in a semi-empirical way. The gaps as a function of the temperature scale with the sublattice magnetizations.

• Received 20 April 1984

DOI:https://doi.org/10.1103/PhysRevB.30.5265