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

Abstract

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 (${E}_{F}$), 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 ${\ensuremath{\lambda}}_{ep}=0.67\ifmmode\pm\else\textpm\fi{}0.05$ and ${\ensuremath{\lambda}}_{ee}\ensuremath{\sim}0.003$, 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 ${\ensuremath{\lambda}}_{ep}(T)$, was consistent with a theoretical calculation based on the Eliashberg function. A quasiparticle peak with a width of $15--20$ meV was found near ${E}_{F}$, 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 (${\ensuremath{\Gamma}}_{0}=0.238\ifmmode\pm\else\textpm\fi{}0.006$ eV).