Local measurement of the Eliashberg function of Pb islands: enhancement   of electron-phonon coupling by quantum well states
  Inelastic tunneling spectroscopy of Pb islands on Cu(111) obtained by scanning tunneling microscopy below 1K provides a direct access to the local Eliashberg function of the islands with high energy resolution. The Eliashberg function describes the electron-phonon interaction causing conventional superconductivity. The measured Eliashberg function strongly depends on the local thickness of the Pb nanostructures and shows a sharp maximum when quantum well states of the Pb islands come close to the Fermi energy. Ab initio calculations reveal that this is related to enhanced electron-phonon coupling at these thicknesses. 
Michael Schackert, Tobias M\"arkl, Jasmin Jandke, Martin H\"olzer,   Sergey Ostanin, Eberhard K. U. Gross, Arthur Ernst an...
cond-mat.supr-con cond-mat.mtrl-sci