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

E. Vincent (1) , V. Dupuis (1) , M. Alba (1) , J. Hammann (1) , J.-P. Bouchaud (1)

1 SPEC - UMR3680 - Service de physique de l'état condensé

We compare aging in a disordered ferromagnet and in a spin glass, by studying the different phases of a reentrant system. We have measured the relaxation of the low-frequency {\it ac} susceptibility $\chi$, in both the {\it ferromagnetic} and {\it spin-glass} phases of a $CdCr_{1.9}In_{0.1}S_4$ 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 by the growth of ferromagnetic domains. We interpret the behaviour observed in the ferromagnetic phase in terms of a combination of {\it domain growth} and {\it pinned wall reconformations,} and suggest that aging in spin glasses is dominated by such wall reconformation processes.

Mots clés: spin glass; relaxation; aging; disordered ferromagnet; domain growth; wall reconformation

Domaines: Physique Générale [physics.gen-ph]; Autre [cond-mat.other]

E. Vincent, V. Dupuis, M. Alba, J. Hammann, J.-P. Bouchaud. Aging phenomena in spin glass and ferromagnetic phases: Domain growth and wall dynamics. EPL - Europhysics Letters, 1999, 50, pp.674-680. ⟨hal-00102715⟩