Equilibrium and off-equilibrium dynamics in a model for vortices in superconductors

Mario Nicodemi; Henrik Jeldtoft Jensen

doi:10.1103/PhysRevB.65.144517

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Equilibrium and off-equilibrium dynamics in a model for vortices in superconductors

Mario Nicodemi, Henrik Jeldtoft Jensen

DOI 10.1103/PhysRevB.65.144517 · Physical Review B

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Abstract

We study a model for the dynamics of vortices in type-II superconductors. In particular, we discuss the magnetization relaxation close to and off equilibrium. At low temperatures a crossover point is found, Tg, where relaxation times become huge and seem to diverge according a Vogel-Tamman-Fulcher law at a lower temperature Tc where a thermodynamic glass transition might be located. Magnetic creep changes by crossing Tg: below Tg, vortex motion is strongly subdiffusive and logarithmic creep is found; above Tg, a power-law creep is asymptotically followed by stretched exponential saturation. The analysis of the self-scattering function also reveals that the dynamical process is non-Gaussian. In the regime below Tg, strong “memory” and “aging” effects appear. In particular, we analyze the properties of “aging” and the structure of its “dynamical scaling.”