Abstract
We present the first experimental determination of the time autocorrelation of magnetization in the nonstationary regime of a spin glass. Quantitative comparison with the response, the magnetic susceptibility , is made by using a new experimental setup allowing both measurements in the same conditions. Clearly, we observe a nonlinear fluctuation-dissipation relation between and , depending weakly on the waiting time . Following theoretical developments on mean-field models, and lately on short range ones, it is predicted that in the limit of long times the relationship should become independent of . A scaling procedure allows us to extrapolate to the limit of long waiting times.
- Received 15 February 2002
DOI:https://doi.org/10.1103/PhysRevLett.88.257202
©2002 American Physical Society