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

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

doi:10.1119/1.3660665

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

Physics Education 2015-06-03 v1 Superconductivity

Authors: 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 \delta ~= 1.53 meV, a lower bound to the Fermi velocity vF >= 3.1 x 10^-7 cm/s, and a BCS coherence length \zeta ~= 43 nm for niobium. These results are in good agreement with previous measurements.

Keywords

point-contact spectroscopy superconductivity niobium Blonder-Tinkham-Klapwijk theory quasiparticle lifetime superconducting gap undergraduate laboratory

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@article{arxiv.1110.6254,
  title  = {Undergraduate experiment in point-contact spectroscopy with a Nb/Au junction},
  author = {L. Janson and M. Klein and H. Lewis and A. Lucas and A. Marantan and K. Luna},
  journal= {arXiv preprint arXiv:1110.6254},
  year   = {2015}
}

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10 pages, 8 figures

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

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