Superconducting phase transitions in ultrathin TiN films
A. V. Rzhanov Institute of Semiconductor Physics SB RAS - 13 Lavrentjev Avenue, Novosibirsk, 630090 Russia
2 Materials Science Division, Argonne National Laboratory - Argonne, IL 60439, USA
3 IMEC Kapeldreef 75 - B-3001 Leuven, Belgium, EU
Accepted: 23 November 2011
Building on the complete account of quantum contributions to conductivity, we demonstrate that the resistance of thin superconducting films exhibits a non-monotonic temperature behaviour due to the competition between weak localization, electron-electron interaction, and superconducting fluctuations. We show that superconducting fluctuations give rise to an appreciable decrease in the resistance even at temperatures well exceeding the superconducting transition temperature, Tc, with this decrease being dominated by the Maki-Thompson process. The transition to a global phase-coherent superconducting state occurs via the Berezinskii-Kosterlitz-Thouless (BKT) transition, which we observe both by power-law behaviour in current-voltage characteristics and by flux flow transport in the magnetic field. The ratio TBKT/Tc follows the universal relation.
PACS: 74.78.-w – Superconducting films and low-dimensional structures / 74.40.-n – Fluctuation phenomena / 74.25.F- – Transport properties
© EPLA, 2012