Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 34: Superconductivity: Tunneling and Josephson Junctions
TT 34.3: Vortrag
Dienstag, 13. März 2018, 10:15–10:30, H 2053
Fluxoid-periodicity crossover from h/2e to h/e in Al nano-loops — •Rebekka Garreis1, Julian Braun1, Christopher Espy1, Omri Sharon2, Florian Strigl1, Yosef Yeshurun2, and Elke Scheer1 — 1Department of Physics, University of Konstanz, 78457 Konstanz, Germany — 2Department of Physics and Institute of Nano Technology and Advanced Materials, Bar-Ilan University, 5290002 Ramat-Gan, Israel
In a multiply connected superconductor, the fluxoid is quantized in units of Φ0 = h/2e, where the 2e is a hallmark of electron pairing in the superconductor. Theoretical studies [1] have predicted that in superconducting nano-loops with length-scale a < ξ0 the dominant periodicity of the flux is 2Φ0 rather than Φ0. Aluminum is a natural choice of material for experimental verification of this prediction because of its relatively large bulk coherence length (ξ0 = 1.6 µm). First measurements on aluminum networks with loop sizes of roughly 320 nm and 420 nm at temperatures between 300 and 1400 mK reveal usual Little-Parks flux periodicity of Φ0 at low temperatures and indicate a crossover to 2Φ0 periodicity at temperatures above 1300 mK. So far, the relatively low critical field of aluminum, in particular close to the transition temperature, and the large period of small loops, allowed the measurement of one Φ0 period only. To be able to achieve a full experimental verification, measurements on networks with a loop size of 500 nm at temperatures between 1100 and 1550 mK are performed.