Spin correlations in RbMnF3at 1.17 TN

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Abstract
Experiments have been performed to measure the scattering function of RbMnF3 at 1.17 TN. In parallel with the experiments a computer simulation has been carried out by solving numerically the motion of spin vectors with the nearest- neighbour Heisenberg exchange interactions appropriate to RbMnF3. Most features of the observed scattering are in good absolute agreement with the predictions of the simulation. These include the appearance of triple-peaked energy spectra near the zone boundary regions of the antiferromagnetic zone, the short-range order at this temperature being sufficient to sustain a quasi-collective type of motion. In addition, critical speeding-up, the increase in the spin diffusion constant near the nuclear reciprocal lattice point, is observed.