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Anodic aluminum oxide templates containing extended arrays of holes with ∼30-nm diameter and approximately 128-nm spacing were sputter-coated with Nb. We find pronounced matching effects in the transport and magnetization measurements beyond 4 kOe. In addition, we observe Little–Parks oscillations of the superconducting critical temperature. We compare the flux pinning in the patterned samples to unpatterned reference samples and find a significant enhancement of the critical current. [Copyright &y& Elsevier]

We present a study of the upper critical field and pinning strength measured by the resistivity and magnetization of a Nb film containing a dense array of 45 nm diameter holes on a hexagonal lattice with a spacing of 101 nm. The holes were formed by self-assembly in anodic aluminum oxide using an electrochemical procedure. Confinement effects and Little–Parks oscillations are seen above 6 K, and strong pinning with matching field effects is seen below 6 K. Above the first matching field interstitial vortices coexist with vortices trapped in the hole array. Pinning in the Nb films with dense hole arrays is enhanced by two orders of magnitude over that in continuous Nb films. At low temperature, flux avalanches are observed and imaged using the magneto-optical Faraday effect. [Copyright &y& Elsevier]