Aging, rejuvenation, and memory effects in short-range Ising spin glass: Cu${}_{0.5}$Co${}_{0.5}$Cl${}_2$-FeCl${}_3$ graphite bi-intercalation compound

Abstract

Non-equilibrium aging dynamics in 3D Ising spin glass Cu${}_{0.5}$Co${}_{0.5}$Cl${}_2$-FeCl${}_3$ GBIC has been studied by zero-field cooled (ZFC) magnetization and low frequency AC magnetic susceptibility ($f=0.05$ Hz), where $T_g=3.92\pm 0.11$ K. The time dependence of the relaxation rate $S(t)=(1/H)$d$M_{ZFC}/$d$\ln t$ for the ZFC magnetization after the ZFC aging protocol, shows a peak at a characteristic time $t_{cr}$ near a wait time $t_w$ (aging behavior), corresponding to a crossover from quasi equilibrium dynamics to non-equilibrium. The time $t_{cr}$ strongly depends on $t_w$, temperature ($T$), magnetic field ($H$), and the temperature shift ($\Delta T$). The rejuvenation effect is observed in both ${\chi }^{\prime }$ and ${\chi }^{\prime \prime }$ under the $T$-shift and $H$-shift procedures. The memory of the specific spin configurations imprinted during the ZFC aging protocol can be recalled when the system is re-heated at a constant heating rate. The aging, rejuvenation, and memory effects observed in the present system are discussed in terms of the scaling concepts derived from numerical studies on 3D Edwards-Anderson spin glass model.

14 pages, 14 figures; Eur. Phys. J. B accepted for publication