Measurement of the Fermi Velocity in Single-Crystal Films of Lead by Electron Tunneling

Abstract
The authors have successfully exploited the Tomasch effect in quasiparticle tunneling from thick, superconducting, single-crystal Pb films to measure Fermi velocities in three high-symmetry directions. Multiple gaps were observed in all of these directions which agree with those reported earlier in bulk single-crystal studies, indicating that these films behave in a fashion similar to bulk Pb.