Correlation satellite driven by reduced dimensionality

Photoelectron spectra of the ordered surface alloy c (2 × 2) CuMn/ Cu(100) show distinct valence band spectral features at higher binding energy, which are most pronounced for the optimal CuMn c (2 × 2) superstructure at half-monolayer Mn deposition. Our analysis comprising resonant photoemission, core level photoemission, inverse photoemission, first-principles local-density calculations, and configuration-interaction cluster-model calculations shows that the data represent the first observation of a valence band satellite caused by the increased electron correlation in an ultrathin metal film.