Nonstationary dynamics in a two-dimensional spin glass

Abstract
Aging is observed in the two‐dimensional short‐range Ising spin glass Rb2Cu0.78Co0.22F4 (Tc = 0 K) by means of low‐frequency ac susceptibility and zero‐field‐cooled (ZFC) magnetization measurements. Below the freezing temperature (∼3.5 K), slow logarithmic relaxations are found in both the in‐phase and out‐of‐phase ac susceptibility, and a waiting time dependence is observed in the relaxation of the zero‐field‐cooled magnetization. No saturation of the relaxations was found. The results suggest that the aging is governed by activated dynamics at length scales smaller than the equilibrium spin‐glass correlation length.