Vortex lattice motion in the flux creep regime on asymmetric pinning potentials

Vortex lattice dynamics is investigated in the adiabatic regime in superconducting/magnetic nanostructures for strong and weak asymmetric pinning potentials, provided by a rectangular array of Ni triangles and a kagome-like array of Ni dots, respectively. The AC voltage response of the AC-driven superconducting vortex lattice is measured in addition to the DC voltage response. The results allow us to link voltage rectification effects with the vortex lattice dynamics. In particular, for the weaker pinning kagome-like array, a high-temperature zero critical current regime is identified, in which both AC and DC voltage responses can be described in terms of a simple model of thermal activation of single vortices over finite asymmetric barriers.