Universality of the dipolar dynamic crossover of cubic ferromagnets aboveTc

In the critical regions of EuS, Cd${\mathrm{Cr}}_2$ ${\mathrm{S}}_4$, and Cd${\mathrm{Cr}}_2$ ${\mathrm{Se}}_4$, the relaxation rates of the magnetization, ${\Gamma }_{{\mathrm{q}}^{=}0}=\left(T\right)\mathrm{}$, quantitatively obey the crossover from speeding up to thermodynamical slowing down, recently calculated by Frey and Schwabl using the coupled-mode approach. Some deviations from this universality occurring in EuO and Ni indicate that, in addition to Heisenberg exchange and dipole-dipole interactions, further effects gain importance, which appear to be absent in ${\Gamma }_{{\mathrm{q}}^{>}0}\left(T_c\right)$.