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

Lucas Janson, Matthew Klein, Heather Lewis, Andrew Lucas, Andrew Marantan, Katherine Luna
2012 American Journal of Physics  
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
more » ... ity 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.
doi:10.1119/1.3660665 fatcat:dl4dtaglhzcunauifrhzz3hlta