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TT: Tiefe Temperaturen

TT 12: Fachsymposium 2: Künstliche Pinning Zentren

TT 12.2: Invited Talk

Tuesday, March 27, 2001, 15:00–15:30, J

Dynamic Phases and Plastic Flow of Vortices in Superconductors with Periodic Pinning: from Devil’s staircases to negative differential conductivity — •Franco Nori — Department of Physics, The University of Michigan, Ann Arbor, MI 48109-1120, USA

We present results from extensive simulations of driven vortex lattices interacting with periodic arrays of pinning sites [1]. Changing an applied driving force produces a very rich variety of novel dynamical plastic flow phases which are very distinct from those observed in systems with random pinning arrays. Signatures of the transitions between these different dynamic phases include sudden jumps in the current-voltage curves as well as marked changes in the vortex trajectories and vortex lattice order. Several novel dynamical phase diagrams are obtained as a function of many physical parameters, including: commensurability, pinning strength, and the degree of spatial order of the pinning sites. These simulations can be a

useful tool for the analysis of the microscopic spatio-temporal dynamics of individual flux-lines in superconductors, lending insight to commonly measured bulk macroscopic quantities such as magnetization and critical currents.

[1] C. Reichhardt, C.J. Olson, and F. Nori, Phys. Rev. Lett. 78, 2648 (1997); Phys. Rev. B 57, 7937 (1998); 58, 6534–6564 (1998); C. Reichhardt and F. Nori, Phys. Rev. Lett. 82, 414 (1999); C. Reichhardt, et al, Phys. Rev. B 54, 16108 (1996).