Magnetotransport properties have been used to investigate vortex phases in Nb films with periodic arrays of magnetic pinning centers. This kind of samples show a continuous glass transition similar to that observed in Nb plain films, but the periodic pinning yields different critical exponents and enhanced glass transition temperature at the matching field. DOI: 10.1103/PhysRevB.72.174512 PACS number͑s͒: 74.78.Ϫw, 74.25.Dw, 74.25.Qt Phase transitions in vortex matter is one of the most interesting research topics, as shown by the flood of papers published during recent years. The phenomenology of vortex phases is especially rich in the case of high critical temperature superconductors ͑HTCS͒, 1 because of the larger anisotropy and thermal fluctuations. Nevertheless, different vortex phases have also been observed in low critical temperature superconductors ͑LTCS͒, including vortex liquid and different vortex solid phases ͑as the vortex-glass 2-4 or the novel Bragg-glass 5,6 ͒. Disorder plays a crucial role in determining which of those phases is stabilized. While materials with weak or no disorder exhibit an Abrikosov vortex-lattice with long-range topological order, random pinning or thermal fluctuations stabilize a Bragg-glass phase with quasi-longrange topological order. 5 The statics of vortex-lattices has been extensively investigated and it is known that a Braggglass undergoes a transition into a disordered vortex-glass 2 or a pinned liquid upon increase of disorder or field, 5 while a different Bose-glass 7,8 may develop in the presence of columnar defects. In Nb single crystals, small angle neutron data have indicated Bragg-glass melting ͑disordering͒.6 In Nb thin films, on the other hand, the logarithmic time decay of the remanent magnetization below the irreversibility line suggested a melting transition of the vortex-lattice, 9 while the negative curvature at low currents of E-J isotherms 10 or their scaling behavior 4 have been discussed to point to the existence of a glass transition. Furthermore aging and memory effects, characteristic of glassy dynamics, have been recently reported by Sun et al. in Nb films covered by a disordered array of magnetic nanoparticles.11 Despite the static properties of the vortex-lattice being largely investigated an open question is how moving lattices ͑for example under the action of a driving current͒ will behave, and how the glassy properties of the static system will be affected by lattice motion. It has been argued that at large vortex velocities disorder would produce little effect since the pinning force on a single vortex varies rapidly.12 On the other hand Giamarchi et al. 13 favor the picture of a moving glass, i.e., glassy properties remain in moving lattices.Most of the experimental studies so far have considered the effect of random disorder. Nanolithography techniques allow fabricating ordered arrays of pinning centers, 14 so that the interaction of vortices with an in-plane periodic distribution of defects can be studied. Such interaction yields dra...