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arXiv · 1110.6254

Undergraduate experiment in point-contact spectroscopy with a Nb/Au junction

L. Janson·M. Klein·H. Lewis·A. Lucas·A. Marantan·K. Luna
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Abstract

We describe an experiment in superconductivity suitable for an advanced undergraduate laboratory. Point-contact spectroscopy is performed by measuring the differential conductance between an electrochemically etched gold tip and a 100-nm superconducting niobium film with a transition temperature Tc ~= 7 K. By fitting the results to Blonder-Tinkham-Klapwijk theory using a finite lifetime of quasiparticles, we obtain a superconducting gap energy δ~= 1.53 meV, a lower bound to the Fermi velocity vF >= 3.1 x 10^-7 cm/s, and a BCS coherence length ζ~= 43 nm for niobium. These results are in good agreement with previous measurements.

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L. Janson, M. Klein, H. Lewis, A. Lucas, A. Marantan, K. Luna. 2011-10-28. Undergraduate experiment in point-contact spectroscopy with a Nb/Au junction. https://doi.org/10.1119/1.3660665

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