Recent experiments on the non-equilibrium dynamics of spin glasses are reviewed. The experiments are discussed within a physical picture based on recent domain pictures of the spin glass phase introduced by Fisher and Huse, and by Koper and Hilhorst.
Some recent experiments on the non‐equilibrium dynamics in two‐ and three‐dimensional spin glasses are reviewed. The experimental results are discussed within new domain (droplet) theories of the spin glass phase. It is found that the experiments convincingly verify some fundamental concepts of these theories. Especially, it is shown that if a spin glass has been ‘‘aged’’ at constant temperature and afterwards subjected to a persistent temperature shift or a temperature cycling, the dynamics are governed by an interplay between the growth of spin glass domains and the overlap length, which is the maximum length scale where equilibrium spin correlations at two nearby temperatures are indistinguishable.
Following a brief introduction to spin-glass systems, the current status of experimental evidence on the occurrence of a phase transition is reviewed. Recent analyses of dynamical properties of spin glasses are discussed in terms of several model predictions, including the conclusion of a divergent relaxation time τ at a finite temperature, although with large, non-mean-field indices z and v. The role of regular terms (leading to corrections to scaling) in the nonlinear response are reviewed, stressing their influence on the evaluation of the susceptibility and order-parameter exponents γ′ and β′.