In situ preparation of Pb-based superconducting thin films at low temperature and low oxidizing atmosphere

Thin films of Pb-based superconductor have been epitaxially grown in situ on MgO (100) substrates by rf-magnetron sputtering. The growth temperature was 550°C, which is relatively low compared to that of conventional oxide-superconducting films. The reducing atmosphere was preferable for the formation of films with Pb-3212 structure, and no oxygen was required in the sputtering gas. The film showed a superconductive transition at 75 K, and zero-resistivity was realized below 60 K without post-heat treatment.