Vortex pinning in superconducting Nb thin films deposited on nanoporous alumina templates

We present a study of magnetization and transport properties of superconducting Nb thin films deposited on nanoporous aluminium oxide templates. Periodic oscillations in the critical temperature vs. field, matching effects in fields up to 700 mT and strongly enhanced critical currents were observed. These fields are considerably higher than those typical for periodic pinning arrays made by lithographic techniques, which reflects the benefits of nanostructuring superconductors by using self-organized growth. This method provides a periodic pinning potential with sub-100 nm spacing between the pinning centers, which enhances vortex pinning in broad field and temperature ranges