Vortex kinks in superconducting films with periodically modulated thickness

Abstract

We report magnetoresistance measurements in Nb films having a periodic thickness modulation. The cylinder shaped thicker 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 resistivity ρ increases monotonously with increasing magnetic field B and the ρ–B characteristics are approximately piecewise linear. The linear ρ versus B segments change their slope at matching fields where the number of vortices is an integer or a half integer times the number of protruding cylinders in the sample. Numerical simulations allow us to associate the different segments of linear magnetoresistance to different vortex-flow regimes, some of which are dominated by the propagation of discommensurations (kinks).

Dynamic Phases and Reentrant Hall Effect for Vortices and Skyrmions on Periodic Pinning Arrays

“…Other aspects have also been explored such as adding asymmetry to the arrays [21], introducing local heating in order to produce both S-shaped and N-shaped velocity-force curves in analogy to those found in conduction curves for semiconductors [22], and inducing density wave propagation [23]. Numerous other studies of superconducting vortices in periodic pinning arrays have revealed multiple depinning transitions, the flow of interstitials, kink flow, and multiple step jumps in the velocity-force curves [24,25,26,27,28,29,30,31,32] Previous studies involved strictly overdamped particles; however, non-dissipative forces can also arise, such as the Magnus gyrotropic force [33,34], which creates a velocity component perpendicular to the forces acting on the particle [33,35]. In superconducting vortex systems, Magnus forces are possible, and experiments have found evidence for transverse motion or the vortex Hall effect [36], with more recent observations showing vortex Hall angles of up to 45 • in certain types of superconducting systems [37].…”

Superconducting heterostructures: from antipinning to pinning potentials

“…Recently, however, the stable vortex structures in thin superconducting films containing superconducting pillars have been studied [5] and the transport in superconducting films with modulated thickness [6] examined. It has been shown that superconducting pillars repel vortices [7], making the array an 'antipinning' periodic landscape that may be viewed as the inverse type of defects to a lattice of antidots or of normal pinning dots.…”