Electron-Phonon Coupling in the Conventional Superconductor YNi2B2C at High Phonon Energies Studied by Time-of-Flight Neutron Spectroscopy

Abstract

We report an inelastic neutron scattering investigation of phonons with energies up to 159 meV in the conventional superconductor YNi2B2C. Using the sweep mode, a newly developed time-of-flight technique involving the continuous rotation of a single crystal specimen, allowed us to measure a four-dimensional volume in (Q, E) space and, thus, determine the dispersion surface and linewidths of the A(1g) (approximate to 102 meV) and A(u) (approximate to 159 meV) type phonon modes over the whole Brillouin zone. Despite of having linewidths of Gamma = 10 meV, A(1g) modes do not strongly contribute to the total electron-phonon coupling constant lambda. However, experimental linewidths show a remarkable agreement with ab initio calculations over the complete phonon energy range, demonstrating the accuracy of such calculations in a rare comparison to a comprehensive experimental data set.