Collapse of the effective response time near the spin glass transition temperature

Kenning et al. discovered the collapse of the effective response time, ${t}_{H}^{\text{eff}}({t}_{\text{w}};T)$, independent of aging time, ${t}_{\text{w}}$, as one approached the spin glass transition temperature ${T}_{\text{g}}$ from below. Nordblad and Lundgren observed the same effect by reducing the temperature from ${T}_{\text{g}}(H)$. We analyze the behavior of $\mathrm{ln}\phantom{\rule{0.16em}{0ex}}{t}_{H}^{\text{eff}}({t}_{\text{w}};T)$ in the temperature range near and below ${T}_{\text{g}}$ using a scaling law that takes into account both the magnetic field $H$ and the time-dependent spin-glass coherence length $\ensuremath{\xi}(t,{t}_{\text{w}};T)$. An overdetermined predictive fit to the experimental data accounts for a quasioscillatory structure of $\mathrm{ln}\phantom{\rule{0.16em}{0ex}}{t}_{H}^{\text{eff}}({t}_{\text{w}};T)$ as a function of magnetic field ${H}^{2}$ for reduced temperatures as large as $T/{T}_{\text{g}}=0.98$.