Critical spin fluctuations in EuO

Zero-field electron-spin resonance was used to measure the spin-relaxation time above $T_c$ in the isotropic ferromagnet EuO. These measurements show an asymptotic behavior in the reduced temperature region $t<~0.02$. The dynamic exponent $z$ was determined for this asymptotic region to be $z=2.04\mathrm{}\left(7\right)\mathrm{}$. Longitudinal relaxation measurements of the kinetic coefficient in EuO of Kötzler et al. [Solid State Commun. 26, 641 (1978)] have been reanalyzed and provide an exponent $z=1.93\mathrm{}\left(10\right)\mathrm{}$ in the asymptotic region. Both values of $z$ agree with theoretical predictions for a dipolar dominated region in $\kappa q$ space.