Superconducting phase transitions in ultrathin TiN films

• Published in: Europhysics letters Vol. 97; no. 1; p. 17012
• Main Authors: Baturina, T. I, Postolova, S. V, Mironov, A. Yu, Glatz, A, Baklanov, M. R, Vinokur, V. M
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.01.2012; EPS, SIF, EDP Sciences and IOP Publishing
• Subjects: 74.25.F; 74.40.-n; 74.78.-w
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/0295-5075/97/17012

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.