Direct observation of the superconducting gap in phonon spectra

Authors :: Weber, F.
Kreyssig, A.
Pintschovius, L.
Heid, R.
Reichardt, W.
Reznik, D.
Stockert, O.
Hradil, K.
Publication Year :: 2008
Abstract: We show that the superconducting energy gap $\Delta$ can be directly observed in phonon spectra, as predicted by recent theories. In addition, since each phonon probes the gap on only a small part of the Fermi surface, the gap anisotropy can be studied in detail. Our neutron scattering investigation of the anisotropic conventional superconductor YNi$_2$B$_2$C demonstrates this new application of phonon spectroscopy.<br />Comment: 4 pages, 5 figures