Vortex-lattices in quasiperiodic pinning potentials

We have investigated vortex-lattice dynamics in superconducting Nb thin films with different types of quasiperiodic arrays of magnetic pinning centers. The mixed-state magnetoresistance show minima for particular applied fields, which reveal matching effects between the vortex-lattice and the quasiperiodic array. These minima are as sharp and well defined as those found with periodic pinning arrays. Moreover, a larger number of minima are observed for quasiperiodic arrays, which in some cases indicate a high ratio of vortices per pinning site. These results suggest that matching between the vortex-lattice and the array of magnetic dots takes place on a very local scale, indicating a short local correlation-length of the vortex-lattice.