Transport current carrying superconducting film with periodic pinning array under strong magnetic fields

Abstract

The transport current carrying dissipative (flux flow) and dissipationless (pinned) vortex configurations and their dynamics are investigated numerically in the framework of the time-dependent Ginzburg-Landau approach. Assuming that magnetic induction is nearly uniform, the model is generalized to include strong inhomogeneous electric fields. Hexagonal array nanoholes of the size of coherence length and density npin was considered for various filling factors [defined as f=B/(Φ0npin)]. The vortex depinning is closely associated with the appearance of a strongly varying electric field. For the matching field, f=1, the critical current is maximal and the transition to the resistive state occurs as a coherent depinning of the entire vortex lattice. For a system with interstitial vortices, f>1, the mechanism of depinning depends on the current direction with respect to the pinning array. There are two qualitatively distinct geometries: the obstacle and channel geometries. In the obstacle geometry lines of interstitial vortices are blocked by strongly pinned vortices, while in the channel geometry the lines move unimpeded confined in channels. It was found that slightly above the critical current the trajectories of the moving vortices are not straight, but rather acquire a snakelike shape enveloping the system of pins. In contrast to f=1, the transition to a resistive state is not coherent and is going through formation of “snakelike” vortex trajectories. The critical current in the obstacle geometry is significantly larger than in the channel one.

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