Spin-Orbit Scattering Effects on the Phonon Emission and Absorption in Superconducting Tunneling Junctions

A phonon spectroscopy experiment reported in a previous Letter shows signals strongly dependent on the applied magnetic field. We investigate the possible physical mechanisms occurring in the superconducting tunneling junctions in order to explain the experimental findings. We show that the electron-phonon interaction combined with the elastic spin-orbit scattering due to surface and impurities effects leads to results in agreement with the experimentally observed signals.