Off-equilibrium fluctuation-dissipation relation in a spin glass
An experimental test for mean-field predictions
Service de Physique de l'État condensé, CEA–Centre de Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, France
Published online: 9 September 2004
We report new experimental results obtained on the insulating spin glass . Our experimental setup allows a quantitative comparison between the thermo-remanent magnetisation and the autocorrelation of spontaneous fluctuations of magnetisation, yielding a complete determination of the fluctuation-dissipation relation. The dynamics can be studied both in the quasi-equilibrium regime, where the fluctuation-dissipation theorem holds, and in the deeply ageing regime. The limit of separation of time-scales, as used in analytical calculations, can be approached by use of a scaling procedure.
PACS: 05.70.Ln – Nonequilibrium and irreversible thermodynamics / 75.50.Lk – Spin glasses and other random magnets / 07.20.Dt – Thermometers / 07.55.Jg – Magnetometers for susceptibility, magnetic moment, and magnetization measurements
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2004