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 (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 lambda(ep) = 0.67 +/- 0.05 and lambda(ee) similar to 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 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 (Gamma(0) = 0.238 +/- 0.006 eV).