Statistical Physics of Fluctuations in Glassy

在这个项目中，通过法国、美国和日本的研究人员以及实验者和理论家的密切合作，研究了支配自旋玻璃等玻璃系统中平衡和非平衡动力学的涨落的基本性质。分组(或个别成员)对系统中的各种主题进行了单独调查，并在讲习班上讨论了结果--1998年10月在法国罗雅蒙特和1999年10月在京都--所有成员都参加了讲习班，以寻找关于玻璃系统波动的共同概念(S)。主要结果如下：1)关于自旋玻璃中的老化现象：a)通过对热剩余磁化强度的详细测量，提取了自旋玻璃(SG)的关联长度，并在实验上建立了它在老化过程中的生长规律(Orbach)。B.)在温移和循环方案中，自旋眼镜展示了…更明显的矛盾现象是“返老还童”和“记忆效应”。从相空间的观点出发，提出了一个理论框架(Bouchaud)，并基于该框架中的“分层随机能量模型”(Nemoto)对该现象进行了数值分析。另一方面，对EA模型中老化现象的模拟结果与描述真实自旋空间中老化现象的液滴图像的预测符合得很好。2)通过无序铁磁体或铁电体中的老化现象与自旋玻璃中的老化现象的比较，提出了前者中的老化动力学可以很好地解释为具有随机势的介质(Bouchaud，Cugliandolo)中的磁畴壁的扩散运动。关于玻璃系统中的相变和涨落的性质，得到了以下新的结果：将SG平均场理论推广到信息的统计计算(Nishimori)，关于矢量自旋玻璃和高T_c陶瓷超导体中的手性玻璃相变的理论(Kawamura)，磁性和超导陶瓷中的一种新型相变(Matsuura)，自旋玻璃和聚合物玻璃中常见的临界涨落中的伸展指数定律(Campbell)，以及清楚地揭示了不均匀性在玻璃系统中各种相变中的作用的涨落测量(Weissman)。较少

In this program, by the close collaboration of the researchers in France, US and Japan, as well as of the experimentalists and theorists, the fundamental nature of fluctuation which govern the equilibrium and non-equilibrium dynamics in glassy systems such as spin glasses has been studied. The various subjects in the systems have been individually investigated by the sub-groups (or individual members), and their results have been discussed in the workshops-at Royaumont, France, October 1998, and at Kyoto, October 1999-which all the members participated to look for a common concept(s) on fluctuations in the glassy systems. The main results obtained are as follows.1) Concerned with the aging phenomena in spin glasses : a) Through the detailed measurement of the thermoremanent magnetization, the spin-glass (SG) correlation length has been extracted and its growth law in aging has been experimentally established (Orbach). b.) In temperature-shift and cycling protocols spin glasses exhibit … More apparently paradoxical phenomena, the 'rejuvenation' and 'memory effect'. A theoretical framework, which is constructed in a viewpoint from the phase space and can explain the phenomena consistently, has been proposed (Bouchaud), and the phenomena are numerically analyzed based on the 'hierarchical random energy model' which is within this framework (Nemoto). c) On the other hand, it has been found that the simulational results on the aging phenomena in the EA model agree well with the predictions from the droplet picture which describes the phenomena in the real spin space.2) From, comparison of the aging phenomena in disordered ferromagnets or ferroelectrics with those in spin glasses, it has been proposed that the aging dynamics in the former materials is well interpreted as the diffusive motion of domain walls in a medium with random potentials (Bouchaud, Cugliandolo).3). The following new results have been obtained on phase transitions and nature of fluctuations in glassy systems : an extension of the SG mean-field theory to the statistical computations of information (Nishimori), theories on the chiral-glass transition in vector spin glasses and in high-Tc ceramic superconductors (Kawamura), a new type of phase transition in magnetic and superconductive ceramics (Matsuura), the stretched exponential law in the critical fluctuation common to spin glasses and polymer glasses (Campbell), and the fluctuation measurement which clearly reveals a role of the inhomogeneity on various phase transition in glassy systems (Weissman). Less