Jorge I. Facio, Anabella Abate, J. Guimpel, Pablo S. Cornaglia
We report magnetoresistance measurements through Nb films with a periodic thickness modulation. The pillar shaped large-thickness regions of the sample, which form a square lattice, act as repulsive centers for the superconducting vortices. For low driving currents along one of the axes of the square lattice, the resistance R increases monotonously with increasing magnetic field B and the R-B characteristics are approximately piecewise linear. The linear R vs B segments change their slope at the matching fields where the number of vortices is an integer times the number of pillars in the sample. Numerical simulations allow us to associate the different segments of linear magnetoresistance to different vortex-flow regimes. We argue that the magnetoresistance below the first matching field is governed by single-vortex physics while at higher fields is dominated by different vortex-soliton regimes.
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http://arxiv.org/abs/1208.4820
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