Comment on ‘‘Temperature dependence of the response time of dilute metallic spin glasses’’

In a recent article Hoogerbeets, Wei-Li Luo and Orbach (HWO) advocate that the time decay of the thermoremanent magnetization below the spin-glass freezing temperature $T_g$ can accurately be described by a stretched exponential functional form: $M_{\mathrm{TRM}}$=$M_0$ exp(-t/${\tau }_p$ ${)}^{1\mathrm{-}n}$ . .sp In this Comment we show that a pure stretched exponential form is never sufficient to describe the relaxation of the magnetization in spin glasses below $T_g$. Inter alia we demonstrate that the exponential temperature and wait-time dependence of the ‘‘apparent response time’’ ${\tau }_p$ obtained by HWO from limited experimental observations, yields large deviations from the real behavior of the relaxation at long observation times.