Static and dynamic properties of Abrikosov vortices in Nb thin films with superconducting pillar landscapes

The static and dynamic properties of Abrikosov vortices in artificially patterned potential landscapes were subject to many experimental and theoretical investigations since the 1960s. Up to now the potential landscapes were in most cases generated by a well-defined distribution of local potential minima, so called pinning sites, for Abrikosov vortices. In this work, we experimentally investigate the properties of vortices in potential landscapes, which are generated by a lattice of superconducting Nb pillars on the top of Nb thin films, used as highly controllable local anti-pinning centers. The structures were fabricated by a combination of lithography and reactive ion etching. We produced several sets with variations in the pillar lattice constant, in the height of the pillars with respect to the film thickness and in the radius of the pillars from one half to a fifth of the lattice constant. By measuring I-V-characteristics for different values of temperature T and applied magnetic field B, we investigate the vortex-pillar interaction with respect to static commensurability effects. The superposition of dc and ac driving currents allows for the investigation of possible phase locking of the vortex motion to the ac drive.