Superconducting Transition and Vortex Pinning in Nb Films Patterned with   Nano-scale Hole-arrays
  Nb films containing extended arrays of holes with 45-nm diameter and 100-nm spacing have been fabricated using anodized aluminum oxide (AAO) as substrate. Pronounced matching effects in the magnetization and Little-Parks oscillations of the superconducting critical temperature have been observed in fields up to 9 kOe. Flux pinning in the patterned samples is enhanced by two orders of magnitude as compared to unpatterned reference samples in applied fields exceeding 5 kOe. Matching effects are a dominant contribution to vortex pinning at temperatures as low as 4.2 K due to the extremely small spacing of the holes. 
U. Welp (1), Z. L. Xiao (1), J. S. Jiang (1), V. K. Vlasko-Vlasov (1),   S. D. Bader (1), G. W. Crabtree (1), J. Liang (2), ...