Momentum-resolved electron-phonon interaction in lead determined by neutron resonance spin-echo spectroscopy

TL;DR

This study uses neutron resonance spin-echo spectroscopy to measure how electron-phonon interactions in lead change with temperature, revealing a linewidth reduction below the superconducting transition and comparing results with theoretical calculations.

Contribution

It provides the first detailed momentum-resolved measurements of electron-phonon interactions in lead across the superconducting transition using neutron resonance spin-echo spectroscopy.

Findings

Observed linewidth reduction of ~6 μeV below Tc for certain phonons.

Electron-phonon contribution aligns with ab-initio calculations but shows notable deviations.

Demonstrated the temperature dependence of phonon linewidths in lead.

Abstract

Neutron resonance spin-echo spectroscopy was used to monitor the temperature evolution of the linewidths of transverse acoustic phonons in lead across the superconducting transition temperature, $T_c$, over an extended range of the Brillouin zone. For phonons with energies below the superconducting energy gap, a linewidth reduction of maximum amplitude $\sim 6 \mu$eV was observed below $T_c$. The electron-phonon contribution to the phonon lifetime extracted from these data is in satisfactory overall agreement with {\it ab-initio} lattice-dynamical calculations, but significant deviations are found.