On the dynamical behaviour of the random anisotropy systems amorphous DyxGd1-xNi

Longitudinal ac susceptibility experiments have been performed on random anisotropy systems of the series DyxGd1-xNi. Usual dynamical scaling forms with a power-law size distribution failed to explain χ'(ω) and χ''ω) variations. Furthermore the π/2 law is not obeyed in these systems because of non-monotonic distribution of relaxation times, and the divergence when ω→0 of the first and upper distribution moments shows that the distribution is slowly decaying. A Cole-Cole model fits fairly well out experimental results and we observe in these alloys a truncated divergence of the time constant τc of the Cole-Cole susceptibility at a finite temperature T0. (orig.)