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

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.

10 pages, 8 figures

References in corpus (4)

• Andreev - Saint James reflections: a probe of cuprate superconductors
• The role of critical current on point contact Andreev Reflection spectrum between a normal metal and a superconductor
• Andreev Reflection in Heavy-Fermion Superconductors and Order Parameter Symmetry in CeCoIn_5
• Construction of a Cantilever-Andreev-Tunneling rig and its applications to superconductors

Cited by in corpus (6)

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• Tip-induced Superconductivity
• A compact inertial nano-positioner operating at cryogenic temperatures