Off-equilibrium fluctuation-dissipation relation in a spin glass

Didier Hérisson (1, 2) , Miguel Ocio (1)

1 SPEC - UMR3680 - Service de physique de l'état condensé
2 SSP - Solid State Physics, Dept of Engineering Sciences

We report new experimental results obtained onthe insulating spin glass CdCrInS_4. Our experimental setup allows a quantitative comparison between thethermo-remanent magnetization and the autocorrelation of spontaneous fluctuations of magnetization, yielding acomplete determination of the fluctuation-dissipationrelation. The dynamics can be studied both in thequasi-equilibrium regime, where the fluctuation-dissipation theorem holds, and in the deeply aging regime. The limit of separation of time-scales, as used in analytical calculations, can be approached by use of a scaling procedure.

Mots clés: FDT; Fluctuation-dessipation theorem; Temperature; Thermometer; Spin glass; aging; off-equilibrium

Domaines: Systèmes désordonnés et réseaux de neurones [cond-mat.dis-nn]

Didier Hérisson, Miguel Ocio. Off-equilibrium fluctuation-dissipation relation in a spin glass. 2004. ⟨hal-00001239v2⟩