Aging phenomena in spin-glass and ferromagnetic phases: Domain growth and wall dynamics

We compare aging in a disordered ferromagnet and in a spin-glass, by studying the different phases of a re-entrant system. We have measured the relaxation of the low-frequency ac susceptibility chi, in both the ferromagnetic and spin-glass phases of a CdCr1.9In0.1S4 sample. A restart of aging processes when the temperature is lowered (chaos-like effect) is observed in both phases. The memory of previous aging at a higher temperature can be retrieved upon re-heating, but in the ferromagnetic phase it can rapidly be erased Ly the growth of ferromagnetic domains. We interpret. the behaviour observed in the ferromagnetic phase in terms of a combination of domain growth and pinned wall reconformations, and suggest that aging in spill-glasses is dominated by such wall reconformation processes.