Aging in two-dimensional Ising spin glasses
A. G. Schins, E. M. Dons, A. F. M. Arts, and H. W. de Wijn
Faculty of Physics and Astronomy, and Debye Institute, Utrecht
University, P.O. Box 80.000, 3508 TA Utrecht, The Netherlands
E. Vincent, L. Leylekian, and J. Hammann
Service de Physique de l'Etat Condensé, Orme des Merisiers,
Commissariat à l'Energie Atomique, Saclay, 91191 Gif-sur-Yvette Cedex,
France
Aging of two-dimensional (2D) Ising spin glasses with short-range
interactions
Rb2Cu1-xCoxF4
(Tc = 0) is studied in the critical regime via the low-frequency
ac susceptibility and via the dc magnetization for x = 0.22 and 0.33.
After quenching to low temperatures, slow logarithmic relaxation is
observed for both the in-phase and out-of-phase ac susceptibilities.
Using the droplet scaling model, the spin-glass correlation length R
is concluded to increase after a temperature quench as R \propto
(ln t)1/\psi, with t in units of some microscopic
time. The exponent \psi = 1.0 ± 0.1 compares with recent theoretical
results and numerical simulations for 2D short-range Ising spin glasses.
The waiting-time dependence found for the field-cooled and
zero-field-cooled dc magnetizations points to a markedly slower crossover
from the quasiequilibrium to the nonequilibrium regime than in 3D. From
experiments with different cooling histories, finally, the equilibrium
spin-glass state is inferred to be strongly dependent on the temperature.