We report a correction of the Curie temperature, $T_c$, for our Mössbauer study of critical spin dynamics in Gd ${\mathrm{}}^{161}$Dy. The revised $T_c$ value, which is 0.4 K lower than previously reported, leads to spin-correlation times that diverge with an exponent w=0.49(5). Though based on a well-defined power law over reduced temperatures ${10}^{\mathrm{-}3}$${<10\mathrm{}}^{\mathrm{-}1}$, this result remains anomalous: It agrees neither with the predictions for the Heisenberg model nor with those for the Ising model.

• Received 28 October 1985

DOI:https://doi.org/10.1103/PhysRevB.33.5070