Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 17: Superconductivity: Properties and Electronic Structure
TT 17.6: Vortrag
Montag, 16. März 2015, 16:15–16:30, H 2053
Long-ranged interactions in thin TiN films at the superconductor-insulator transition? — •Klaus Kronfeldner1, Tatyana Baturina2, and Christoph Strunk1 — 1Institute for Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany — 2A. V. Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090, Russia
We measured IV-characteristics and magnetoresistance of square TiN-films in the vicinity of the disorder-tuned superconductor-insulator transition (SIT) for different sizes (5µm to 240µm). While the films are superconducting at zero magnetic field, at finite fields a SIT occurs. The resistance shows thermally activated behaviour on both sides of the SIT. Deep in the superconducting regime the activation energy grows linear with the sample size as expected for a size-independent critical current density. Closer to the SIT the activation energy becomes clearly size independent. On the insulating side the magnetoresistance maximum and the activation energy both grow logarithmically with sample size which is consistent with a size-limited charge BKT (Berezinskii-Kosterlitz-Thouless) scenario. In order to test for the presence of long-ranged interactions in our films, we investigate the influence of a topgate. It is expected to screen the possible long-ranged interactions as the distance of the film to the gate is much shorter than the electrostatic screening length deduced from the size-dependent activation energy.