Abstract
Perturbed γγ angular-correlation experiments on oriented single crystals of Gd, containing 1 ppb of In, demonstrate that critical spin fluctuations are isotropic to within about 1 K above the Curie temperature. Closer to we find evidence that the critical spin fluctuations fall increasingly along the c axis. Analysis of nuclear relaxation times in the isotropic region leads to spin autocorrelation times that diverge with an exponent w=0.53(8). This value is not consistent with either spin-nonconserved Heisenberg behavior or Ising behavior, but agrees with Mössbauer data for Gd Dy.
- Received 12 November 1985
DOI:https://doi.org/10.1103/PhysRevB.33.4747
©1986 American Physical Society