Vortices in two-dimensional superconducting weakly coupled wire networks

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Abstract
We have fabricated superconducting weakly coupled wire networks made in thin amorphous niobium-silicon films of high normal-state resistivity and have investigated vortex dynamics in these networks. For the temperatures of interest, the wires have a width in the order of, and a length much larger than the Ginzburg-Landau (GL) coherence length. We find that the vortex mobility in the wire networks is much lower than in Josephson junction arrays. The ratio of the length of the single wires to the GL coherence length determines whether a Kosterlitz-Thouless-Berezinskii transition can be observed in zero field, as well as oscillations at low temperatures in the magnetoresistance. At low temperatures the critical current does not show oscillations in a magnetic field, which might be a consequence of the existence of special vortex configurations in networks with a linear current-phase relation.