Photoemission spectroscopy of the strong-coupling superconducting transitions in lead and niobium

Phys Rev Lett. 2000 Aug 28;85(9):1966-9. doi: 10.1103/PhysRevLett.85.1966.

Abstract

We study the changes in the electronic structure associated with low- T(c) strong-coupling superconducting transitions in Pb and Nb using ultrahigh-resolution (2.3 meV) temperature-dependent (5.3-12.0 K) photoemission spectroscopy. We observe peaks in the density of states on entering the superconducting-phase accompanying gap formation and spectacular redistribution of spectral weight at low energy scales as a function of temperature. The well-known peak-dip feature of the high- T(c) cuprates is seen in Pb, making it a characteristic of strong-coupling superconductivity.