Superconducting Vortex Motion on Magnetic Potentials Made with Arrays of Spin-Ice Nanomagnets.

Electron Beam Lithography has been used to pattern arrays with honeycomb shapes on Si substrates. Sputtering and lift-off techniques are used to obtain a honeycomb array of Co connected nanolines. On top of this array a Nb superconducting film is deposited and a cross-shaped bridge is defined for transport measurements. We have explored the vortex dynamics of these hybrid samples. Different scenarios are studied depending on the magnetic states in the Co honeycomb network: i) Demagnetized state, what allows studying vortex motion and cage potentials; ii) Remanent magnetic states, which allow studying vortex motion in magnetic potentials with magnetic frustration showing different spin-ice configurations: 1) Remanent magnetic state achieved by saturating magnetic fields perpendicular to two opposite sides of the hexagon and 2) Remanent magnetic state obtained with saturating magnetic fields parallel to two opposite sides of the hexagon. In both cases, the different magnetic polarity of the hexagon vertices attracts (pinning centers) or repels (antipining centers) vortices and, in comparison with the demagnetized case, a distinct behavior of the vortex motion is achieved.