Proximity-induced superconductivity in crystalline Cu and Co nanowires and nanogranular Co structures

We report an experimental study of proximity effect-induced superconductivity in crystalline Cu and Co nanowires and a nanogranular Co nanowire structure in contact with a superconducting W-based floating electrode (inducer). For electrical resistance measurements up to three pairs of Pt-based volta...

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Bibliographic Details
Published in:Journal of applied physics 2014-08, Vol.116 (7)
Main Authors: Kompaniiets, M., Dobrovolskiy, O. V., Neetzel, C., Begun, E., Porrati, F., Ensinger, W., Huth, M.
Format: Article
Language:English
Subjects:
Applied physics
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
Cobalt
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
COOPER PAIRS
Crystal structure
Crystallinity
DISTANCE
Electric contacts
ELECTRIC POTENTIAL
ELECTRODES
Floating structures
LENGTH
MAGNETIC FIELDS
MICROSTRUCTURE
Nanowires
Proximity
PROXIMITY EFFECT
Proximity effect (electricity)
QUANTUM WIRES
SPIN
SUPERCONDUCTIVITY
TRIPLETS
WIRES
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Summary:We report an experimental study of proximity effect-induced superconductivity in crystalline Cu and Co nanowires and a nanogranular Co nanowire structure in contact with a superconducting W-based floating electrode (inducer). For electrical resistance measurements up to three pairs of Pt-based voltage leads were attached at different distances beside the inner inducer electrode, thus allowing us to probe the proximity effect over a length of 2–12 μm. Up to 30% resistance drops with respect to the normal-state value have been observed for the crystalline Co and Cu nanowires when sweeping the temperature below Tc of the inducer (5.2 K). By contrast, relative R(T) drops were found to be an order of magnitude smaller for the nanogranular Co nanowire structure. Our analysis of the resistance data shows that the superconducting proximity length in crystalline Cu and Co is about 1 μm at 2.4 K, attesting to a long-range proximity effect in the Co nanowire. Moreover, this long-range proximity effect is insusceptible to magnetic fields up to 11 T, which is indicative of spin-triplet pairing. At the same time, proximity-induced superconductivity in the nanogranular Co nanowire is strongly suppressed due to the dominating Cooper pair scattering caused by its intrinsic microstructure.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4893549