Session I: Vortex Dynamics

I-1: Dynamics of disordered elastic systems

Thierry Giamarchi
University of Geneva, Switzerland

The competition between disorder and elasticity leads to glassy physics. This physics manifests itself in the static properties, leading to phases such as the Bragg glass phase, but also in the dynamics. The disorder leads to pinning at zero temperature, while the divergent barriers of the glass lead to creep motion at finite temperature. Glassiness manifests itself in other ways, such as in the aging of various observables. I will examine these effects both for interfaces and periodic systems.

I-2: Dynamics of the vortex matter in the presence of quenched disorder

Baruch Rosenstein
National Center for Theoretical Sciences and National Chiao Tung University, Taiwan

The Martin-Siggia-Rose method is applied to the Ginzburg-Landau model in the presence of disorder beyond linear response. This allows calculation of the critical current and the I-V curves. The results are different from accepted ones, but are consistent with data in which the (significant) edge contribution is subtracted. The peak effect is interpreted in a way very different from the conventional explanation.

I-3: Simulations on dynamics of vortices driven through random media

X. Hu and M.-B. Luo
National Institute for Materials Science, Tsukuba, Japan

Using dynamical computer simulation we have investigated vortex matters in glass states. A genuine continuous depinning transition is observed at zero temperature, which also governs the low-temperature creep motion. With the notion of scaling, we evaluate in high accuracy critical exponents and scaling functions; we observe a non-Arrhenius creep motion for weak collective pinning where Bragg glass (BrG) is stabilized at equilibrium, while for strong pinning the well-known Arrhenius law is recovered. In both cases, a sharp crossover takes place between depinning and creep at low temperatures. The possible relation between the present results and a recent experimental observation of a second-order like phase boundary inside the BrG phase is discussed.

Reference:
M.-B. Luo and X. Hu: cond-mat/0612051

I-4: Dynamics of driven vortices of HTSC : Scaling, friction, viscosity

Atsutaka MAEDA
Department of Basic Sciences, University of Tokyo, Japan

Dynamics and dynamic phase diagram of driven vortices are ones of the most important subjects concerning on the physics and application of high-T_c superconductivity. We investigate I-V characteristics of cuprate superconductors with different types of pinning, anisotropy etc. with particular interest in (1) investigation of the scaling relation proposed quite recently by Luo and Hu, and (2) links to the physics of friction at the solid interface. In terms of the latter interest, we will also discuss the critical current as a function of waiting time. Another important aspect is the movement of the individual vortex, which is dominated by the quasiparticles inside the core. Based on the experimental data, I will discuss the mechanism which dominate the vortex viscosity.