Pinning Effects in Nb Thin Films with Different Geometries of Artificial Pinning Arrays

Nb films with periodic pinning arrays show matching effects in the magnetic field dependence of the resistivity and the critical current density. The magnetic fields at which these matching effects occur can be very well described in terms of matching fields (Hn), which only depend on the density of pinning centers. In addition, this can be clearly seen in the way that the matching fields Hn vary for diffident geometries of the pinning center arrays, which have different pinning center densities.