  Aging phenomena of short-range Ising spin glass models have been investigated
using Monte Carlo simulations. It is found that in the low-temperature
spin-glass phase the mean domain size exhibits a crossover from a power-law
growth associated with the critical fluctuation at the transition temperature
to slower growth inherent in the low-temperature phase. The temperature
dependence of the growth law of the domain size can be almost explained by this
crossover. We also find that the spin-autocorrelation function in the
quasi-equilibrium regime follows the expected scaling behavior from the droplet
theory expressed in terms of the mean domain size and a characteristic length
scale of droplet excitations.
