Statistical Physics of Fluctuations in Glassy

玻璃态涨落的统计物理

• 批准号: 10044064
• 负责人: TAKAYAMA Hajime
• 金额: $ 3.58万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10044064/
• 关键词: glassy system; spin glass; aging phenomena; EA model; droplet picture; mean-field theory; chiral glass; critical fluctuation; 巨大磁気抵抗系; ドメイン成長; ガラス転移; 階層的自由エネルギー構造; 動的平均場理論; スピングラス相転移

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

在这个项目中，通过法国、美国和日本的研究人员以及实验学家和理论家的密切合作，研究了控制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。各小组（或个别成员）分别对系统中的各种主题进行了研究，并在1998年10月在法国Royaumont和1999年10月在京都举行的研讨会上讨论了他们的结果，所有成员都参加了这些研讨会，以寻求关于玻璃系统波动的共同概念。得到的主要结果如下：1)关于自旋玻璃中的时效现象：a)通过对热磁化强度的详细测量，提取了自旋玻璃（SG）相关长度，并通过实验建立了其在时效过程中的增长规律（Orbach）。b。)在温度变换和循环协议中，旋转玻璃表现出……更明显的矛盾现象，即“返老返老”和“记忆效应”。已经提出了一个从相空间的角度构建的理论框架，可以一致地解释这些现象（Bouchaud），并基于该框架内的“分层随机能量模型”（Nemoto）对这些现象进行了数值分析。c)另一方面，EA模型对老化现象的模拟结果与描述真实自旋空间现象的液滴图的预测结果吻合较好。2)将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进行比较，提出无序铁磁体或铁电体中的老化动力学可以很好地解释为畴壁在随机电位介质中的扩散运动（Bouchaud, Cugliandolo）。关于玻璃系统的相变和涨落性质，获得了以下新结果：将SG平均场理论推广到信息统计计算（Nishimori），关于矢量自旋玻璃和高tc陶瓷超导体中的手性玻璃转变理论（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共有的临界涨落中的拉伸指数定律（Campbell），以及涨落测量，它清楚地揭示了非均匀性对玻璃系统中各种相变的作用（Weissman）。少

项目成果

K.Hukushima: "Chiral Glass Transition and Replica Symmetry Breaking of a Three Dimensional Heisenberg Spin Glass"Phys.Rev.. E61. R1008-1011 (2000)

K.Hukushima：“三维海森堡自旋玻璃的手性玻璃转变和复制对称性破缺”Phys.Rev..E61。

M. Sasaki and K. Nemoto: "Aging Phenomena in the Multi-layer Random Energy Model"J. Phys. Soc. Jpn. Suppl.. (to appear). (2000)

M. Sasaki 和 K. Nemoto：“多层随机能量模型中的老化现象”J。

D. Petit, L. Fruchter and I.A. Campbell: "Ordering in a Spin Glass under Applied Magnetic Field"Phys. Rev. Lett.. 83. 5130-5133 (1999)

D. Petit、L. Fruchter 和 I.A.

Y. G. Joh, R. Orbach, G. G. Wood, J. Hammann, and E. Vincent: "Finite Size Effects on Spin Glass Dynamics"J. Phys. Soc. Jpn. Suppl.. (to appear). (2000)

Y. G. Joh、R. Orbach、G. G. Wood、J. Hammann 和 E. Vincent：“旋转玻璃动力学的有限尺寸效应”J.

J. R. Petta, M. B. Weissman and G. Durin: "Barkhausen Pulse Structure in an Amorphous Ferromagnet : Characterization by High-Order Spectra"Phys. Rev. E. 57. 6363-6369 (1998)

J. R. Petta、M. B. Weissman 和 G. Durin：“非晶铁磁体中的巴克豪森脉冲结构：高阶光谱表征”Phys。