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 A1g (≈102 meV) and Au (≈159 meV) type phonon modes over the whole Brillouin zone. Despite of having linewidths of Γ = 10 meV, A1g modes do not strongly contribute to the total electron-phonon coupling constant λ. 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.