Energy Gaps and Kohn Anomalies in Elemental Superconductors

• DOI: 10.1126/science.1154115
• Publication Date: 2008-02-22T02:23:10Z
• Authors: P. Aynajian; T. Keller; L. Boeri; S. M. Shapiro; K. Habicht; B. Keimer
• Keywords: Superconductivity (cond-mat.supr-con); Condensed Matter - Strongly Correlated Electrons; Multidisciplinary; Strongly Correlated Electrons (cond-mat.str-el); Condensed Matter - Superconductivity; FOS: Physical sciences; 7. Clean energy

The momentum and temperature dependence of the lifetimes of acoustic phonons in the elemental superconductors lead and niobium were determined by resonant spin-echo spectroscopy with neutrons. In both elements, the superconducting energy gap extracted from these measurements was found to converge with sharp anomalies originating from Fermi-surface nesting (Kohn anomalies) at low temperatures. The results indicate electron many-body correlations beyond the standard theoretical framework for conventional superconductivity. A possible mechanism is the interplay between superconductivity and spin- or charge-density-wave fluctuations, which may induce dynamical nesting of the Fermi surface.