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Title: 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 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 T{sub c} 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.
Authors:
; ; ;  [1] ;  [1] ;  [2] ; ;  [3]
  1. Physikalisches Institut, Goethe University, 60438 Frankfurt am Main (Germany)
  2. (Ukraine)
  3. Department of Materials Science, TU Darmstadt, 64287 Darmstadt (Germany)
Publication Date:
OSTI Identifier:
22314304
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COOPER PAIRS; DISTANCE; ELECTRIC POTENTIAL; ELECTRODES; LENGTH; MAGNETIC FIELDS; MICROSTRUCTURE; PROXIMITY EFFECT; QUANTUM WIRES; SPIN; SUPERCONDUCTIVITY; TRIPLETS; WIRES