Regensburg 2022 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 30: Superconductivity: Poster Session
TT 30.24: Poster
Thursday, September 8, 2022, 15:00–18:00, P1
Superconductor-insulator transition in ultra-thin granular aluminum films — •Thomas Huber1, Aviv Moshe2, Guy Deutscher2, and Christoph Strunk1 — 1Institute for Experimental and Applied Physics, University of Regensburg, Regensburg, Germany — 2Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
The relation between homogenously disordered and granular superconductors is so far not clearly understood. In particular, the existence of highly insulating states in grAl has yet not been demonstrated. Here we investigate ultra-thin grAl films in the truely 2D limit and find a superconducting transition for sample S with R(4K) ≈ 3kΩ and insulating behavior for sample I with R(4K) ≈ 7.75kΩ (d-SIT). By increasing the perpendicular magnetic field we drive both samples (deeper) into the insulating regime (B-SIT), where we find activated behavior in a temperature range T*(B) < T < ≈ 800mK. For T < T* and B < ≈ 1T, the R(T) curves saturate, indicating an intermediate anomalous metallic state [1] on both sides of the SIT [2]. The resistance R, the activation energy EA and the threshold voltage VT depend on magnetic field and show strong similarities to the behavior of both regular Josephson junction arrays [3] and homogenously disordered films [4].
[1] A. Kapitulnik et al., Rev. Mod. Phys. 91, 011002 (2019)
[2] X. Zhang et al., arXiv:2201.08801 [cond-mat.supr-con] (21.01.2021)
[3] P. Delsing et al., AIP Conference Proceedings 427, 313 (1998)
[4] T.I. Baturina et al., Phys. Rev. Lett. 99, 257003 (2007)