Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 19: Superconductivity: Poster Session
TT 19.7: Poster
Montag, 7. März 2016, 15:00–18:00, Poster D
Test for the presence of long-ranged Coulomb interactions in thin TiN films near 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, Russia
We have measured the conductance of square shaped TiN films on the superconducting and the insulating side of the superconductor/insulator transition. The conductance shows thermally activated behaviour with an activation energy kBT0(L) ∝ lnL, with L being the lateral size of the squares. Such behavior is consistent with 2D long-ranged Coulomb interactions with a large electrostatic screening length Λ ≃ 200 µm [1].
To independently test whether long ranged Coulomb interactions can be responsible for the observed size dependence we compare R(T,B) of a large TiN film in the critical region with and without a screening Pd layer in a distance t ≈ 60 nm to the TiN film.
The screening Pd-layer is expected to reduce the activation energy from ∝ ln[min(L,Λ)] to ∝ ln(t) and the thermally activated resistance in films with L≳ Λ by the large number Λ/t≃ 3000.
In contrast, our experiment showed no significant reduction of R(T) and T0. This suggests that the measured size dependent conductance of our TiN film is not related to long-ranged Coulomb interactions.
[1] M. V. Fistul, V. M. Vinokur, and T. I. Baturina,
PRL 100, 086805 (2008).