Commensurability effects in superconducting Nb films

ABATE ANABELLA; JORGE FACIO; PABLO CORNAGLIA; GUIMPEL JULIO

Rio de Janeiro

Workshop; 7th FAPERJ Workshop: The dynamics and assembly of soft structures; 2014

ICAM

We have studied the effects of commensurability between a superconducting vortex lattice and a periodic grid of defects. We fabricated two samples with different kind of defects. The first sample consisted of a Nb film having periodic thickness modulations that act as repulsive centers for the superconducting vortices. The second sample consisted of a Nb film with periodic rectangular arrays of Ni sub-micrometric dots that acts as attractive centers for the vortex. Electrical resistivity measurements were carried out in a four-probe geometry while a magnetic field was applied perpendicular to the sample surface. In both samples, we observed commensuration of the vortex lattice to the defect grid when the number of flux quanta per grid cell is an integer or a half integer number. The obtained results for the sample with repulsive centers were compared with numerical simulations.