Hérisson D, Ocio M
DSM/Service de Physique de l'Etat Condensé, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France.
Phys Rev Lett. 2002 Jun 24;88(25 Pt 1):257202. doi: 10.1103/PhysRevLett.88.257202. Epub 2002 Jun 6.
We present the first experimental determination of the time autocorrelation C(t',t) of magnetization in the nonstationary regime of a spin glass. Quantitative comparison with the response, the magnetic susceptibility chi(t',t), is made by using a new experimental setup allowing both measurements in the same conditions. Clearly, we observe a nonlinear fluctuation-dissipation relation between C and chi, depending weakly on the waiting time t'. Following theoretical developments on mean-field models, and lately on short range ones, it is predicted that in the limit of long times the chi(C) relationship should become independent of t'. A scaling procedure allows us to extrapolate to the limit of long waiting times.
我们展示了自旋玻璃非平稳状态下磁化强度时间自相关函数(C(t',t))的首次实验测定。通过使用一种新的实验装置，在相同条件下进行这两种测量，对响应（即磁化率(\chi(t',t))）进行了定量比较。显然，我们观察到(C)与(\chi)之间存在非线性涨落 - 耗散关系，且该关系对等待时间(t')的依赖较弱。根据平均场模型以及近期短程模型的理论发展，预计在长时间极限下，(\chi(C))关系应与(t')无关。一种标度程序使我们能够外推到长等待时间极限。
