Coupling parameters of many-body interactions for the Al(100) surface state: A high-resolution angle-resolved photoemission spectroscopy study

We examined the dimensionless coupling parameters of many-body interactions for a free-electron-like surface-derived state in Al(100) by means of high-resolution angle-resolved photoemission spectroscopy. A kink structure was found to exist in the energy-band dispersion near the Fermi level (EF ), which was attributed to the electron-phonon interaction. At 50 K, the coupling parameters of the electron-phonon and electron-electron interactions were estimated as λep = 0.67 ± 0.05 and λee ∼ 0.003, respectively, indicating that the effective mass enhancement was mainly derived from the electron-phonon interaction. The temperature dependence of the kink structure, as measured by λep (T ), was consistent with a theoretical calculation based on the Eliashberg function. A quasiparticle peak with a width of 15–20 meV was found near EF , which was explained well by the simulated spectral function incorporating the self-energy evaluated in this study. We found that the electrons at the surface were strongly scattered by the defects at the surface and that the linewidth was significantly broadened ( 0 = 0.238 ± 0.006 eV).