Mechanisms of periodic pinning in superconducting thin films

We studied the changes in the superconducting properties of Nb films due to an array of Ni dots used as collective pinning sites. To determine the pinning mechanism, thin Ag layers of varying thicknesses were deposited on the Ni dots prior to the Nb film deposition. The Ag deposited on the pinning dots has little effect on the collective pinning phenomena, which implies that the main pinning mechanism is of magnetic origin.Received: 3 February 2004, Published online: 31 August 2004PACS: 74.25.Qt Vortex lattices, flux pinning, flux creep - 74.78.-w Superconducting films and low-dimensional structures