Volume 102, Number 6, June 2013
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||10 July 2013|
Experimental study of the intrinsic multiple Andreev reflections effect in GdO(F)FeAs superconductor array junctions
1 P.N. Lebedev Physical Institute of the RAS - 119991 Moscow, Russia
2 M.V. Lomonosov Moscow State University - 119991 Moscow, Russia
3 International Laboratory of High Magnetic Fields and Low Temperatures - 53-421 Wroclaw, Poland, EU
4 Institute for High Pressure Physics of the RAS - 142190 Troitsk, Russia
Received: 25 February 2013
Accepted: 3 June 2013
We report the first observation of the intrinsic multiple Andreev reflections effect (IMARE) in S-n-S-…-S arrays (S = superconductor, n = normal metal) formed by a “break-junction” technique in the GdO(F)FeAs superconductor (TC = (48–53) K). We show that superconducting gap peculiarities in dI/dV spectra sharpen dramatically in the arrays as compared with that in the single-contact spectra; this enables to improve significantly the accuracy of the bulk superconducting parameters determination. By using IMARE, we determined the large- and the small-gap values ΔL = 11.0 ± 1.1 meV and ΔS = 2.6 ± 0.4 meV. The BCS ratio 2ΔL/kBTClocal = 5.0–5.9 > 3.52 (TClocal is the contact area critical temperature) evidences a strong electron-boson coupling. The results obtained agree well with our previous data by Andreev spectroscopy for single SnS contacts.
PACS: 74.45.+c – Proximity effects; Andreev reflection; SN and SNS junctions / 74.70.Xa – Pnictides and chalcogenides / 74.25.-q – Properties of superconductors
© EPLA, 2013
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