Spin Fluctuations in EuS Above T/sub C/: Comparison with Asymptotic Renormalization-Group Theory

摘要

Constant energy scans in neutron scattering provide a very sensitive tool for theoretical line shapes in detail. In order to verify the predictions of asymptotic renormalization group theory for isotropic ferromagnets above T/sub c/ we measured the temperature dependence of the paramagnetic scattering from the Heisenberg ferromagnet EuS. The width of the constant E peaks increases with increasing temperature as predicted. Surprisingly the positions do not scale. The nonuniversal behaviour is attributed to the crossover from isotropic to dipolar dynamics. 11 refs. (ERA citation 12:049879)