Browsing by Author "Assi, H."

Now showing 1 - 5 of 5
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    Disordered vortex matter out of equilibrium: a Langevin molecular dynamics study
    Assi, H.; Chaturvedi, H.; Dobramysl, U.; Pleimling, Michel J.; Täuber, Uwe C. (2015-11-04)
    We discuss the use of Langevin molecular dynamics in the investigation of the non-equilibrium properties of disordered vortex matter. Our special focus is set on values of system parameters that are realistic for disordered high-$T_c$ superconductors such as YBCO. Using a discretized elastic line model, we study different aspects of vortices far from thermal equilibrium. On the one hand we investigate steady-state properties of driven magnetic flux lines in a disordered environment, namely the current-voltage characteristics, the gyration radius, and the pinning time statistics. On the other hand we study the complex relaxation processes and glassy-like dynamics that emerge in type-II superconductors due to the intricate competition between the long-range vortex-vortex repulsion and flux pinning due to randomly placed point defects. To this end we consider different types of sudden perturbations: temperature, magnetic field, and external current quenches.
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    Flux line relaxation kinetics following current quenches in disordered type-II superconductors
    Chaturvedi, H.; Assi, H.; Dobramysl, U.; Pleimling, Michel J.; Täuber, Uwe C. (2016-06)
    We investigate the relaxation dynamics of magnetic vortex lines in type-II superconductors following rapid changes of the external driving current by means of an elastic line model simulated with Langevin molecular dynamics. A system of flux vortices in a sample with randomly distributed point-like defects is subjected to an external current of appropriate strength for a sufficient period of time so as to be in a moving non-equilibrium steady state. The current is then instantaneously lowered to a value that pertains to either the moving or pinned regime. The ensuing relaxation of the flux lines is studied via one-time observables such as their mean velocity and radius of gyration. We have in addition measured the two-time flux line height autocorrelation function to investigate dynamical scaling and aging behavior in the system, which in particular emerge after quenches into the glassy pinned state.
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    Relaxation dynamics in type-II superconductors with point-like and correlated disorder
    Dobramysl, U.; Assi, H.; Pleimling, Michel J.; Täuber, Uwe C. (Springer, 2013-05-01)
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    Relaxation dynamics of vortex lines in disordered type-II superconductors following magnetic field and temperature quenches
    Assi, H.; Chaturvedi, H.; Dobramysl, U.; Pleimling, Michel J.; Täuber, Uwe C. (American Physical Society, 2015-11-17)
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    Structural Relaxation and Aging Scaling in the Coulomb and Bose Glass Models
    Assi, H.; Chaturvedi, H.; Pleimling, Michel J.; Täuber, Uwe C. (2016-08-13)
    We employ Monte Carlo simulations to study the relaxation properties of the two-dimensional Coulomb glass in disordered semiconductors and the three-dimensional Bose glass in type-II superconductors in the presence of extended linear defects. We investigate the effects of adding non-zero random on-site energies from different distributions on the properties of the correlation-induced Coulomb gap in the density of states (DOS) and on the non-equilibrium aging kinetics highlighted by the density autocorrelation functions. We also probe the sensitivity of the system's equilibrium and non-equilibrium relaxation properties to instantaneous changes in the density of charge carriers in the Coulomb glass or flux lines in the Bose glass.