Transition and Dynamics in Complex Systems

在该项目的过程中，几名成员及其合作者在两国（法国和美国）和日本之间进行了单独交流。这两次研讨会分别于1994年10月17- 18日在筑波大学和1995年12月4- 6日在CEA-Saclay举行。1）自旋玻璃（SG's）的相变和动力学：Takayama通过计算方法证明了“Griffiths相”中的慢动力学由两个过程组成，普通临界动力学和团簇动力学，而坎贝尔指出了Ising SG's的非普适性。Ito观察到在向混合相的折返转变点处的非线性磁化率中存在发散的平衡。2）SG在磁场中的老化现象：Ocio已经为TRM和TRM的时间发展找到了一个通用的缩放形式，包括它们的等待时间依赖性，而Orbach提出了一种从观察到的老化现象中提取重叠函数P（q）的方法。3）颗粒（陶瓷）超导体中的相动力学：根据对1/f噪声的测量，Ocio指出了π结的可能存在，Kawamura提出了这些系统中“手征”的随机冻结理论。4）重电子系统Ce（Ru_<0.85>Rh_<0.15>）_2Si_2：在这种材料中，宫古已经观察到从高温定域自旋态到低温重电子态的交叉，5）（TMTSF）_2PF_6中的自旋密度波（SDW）动力学：Clark发现，在高温下，SDW的回复过程受热激发准粒子的控制，而在低温下则受它们的量子隧穿控制。6）相变的一般理论：铃木发展了一般理论，如“指数算子的分解”，并将其应用于各种具有奇异相变的系统。

In the course of the project several members and their collaborators were individually exchanged between the two countries (France and US) and Japan. The two workshops were held ; one on October 17-18,1994 at University of Tsukuba, and the other entitled "Physics of Frustrated Systems" on December 4-6,1995 at CEA-Saclay. Below we briefly describe the main results obtained by the project.1) Transitions and Dynamics in spin glasses (SG's) : By the computational method Takayama has shown that slow dynamics in the 'Griffiths phase' consists of two processes, ordinary critical dynamics and cluster dynamics, while Campbell has pointed out a non-universal nature of Ising SG's. Ito has observed a divergent bahavior in the nonlinear susceptibility at the reentrant transition point to the mixed phase.2) Aging Phenomena in SG's in Magnetic Fields : Ocio has found a universal scaling form for the time development of TRM and IRM including their waiting time dependence, while Orbach has proposed a way to extract the overlap function P (q) from the observed aging phenomena.3) Phase Dynamics in Granular (Ceramic) Superconductors : From the measurement on 1/f noise Ocio has pointed out a possible existence of pi-junction, and Kawamura has developed a theory of the random freezing of 'chiralities' in these systems.4) Heavy Electron Systems Ce (Ru_<0.85>Rh_<0.15>)_2Si_2 : In this material Miyako has observed the crossover from the high-T localized spin state to the low-T heavy electron state, and then to the spin-density wave (SDW) phase associated with the INVAR effect.5) SDW Dynamics in (TMTSF)_2PF_6 : Clark has found that the repining process of SDW is governed by thermally excited quasi-particles at high T,but by their quantum tunneling at low T.6) General Theory for Phase Transitions : Suzuki has developed general theories, such as the 'decomposition of exponential operators', and has applied them to various systems with exotic phase transitions.