Evolution of the electronic structure during the epitaxial growth of Au on Pt(100)

We report an angle-resolved photoemission study of the electronic structure of Au layers grown epitaxially on Pt(100) in the coverage range 1-10 monolayers (ML). Our results include an analysis of the electronic band structure and the Fermi surface, combined with structural information from low-energy electron diffraction. The Au films grow epitaxially with a (1 × 1) pattern up to 4-5 ML. We monitor the electronic band structure near the surface X¯-point vs. Au coverage. In the 1-3 ML range we observe interface electronic states related to the formation of a Au-Pt alloy in this coverage range. Starting at 2-3 ML coverage, we identify quantum well states from the incipient Au sp band, which converge into a bulk like Au sp band near 6 ML. After 5-6 ML, a (1 × 7) pattern is observed, due to the formation of a surface reconstruction in the epitaxial Au film with a topmost hexagonal layer, as in the reconstruction of bulk Au(100). We identify specific electronic states of quasi-one-dimensional character coming from the corrugated hexagonal layer. We obtain a complete picture and understanding of the electronic structure of Au/Pt(100), including sp Au band formation, hybridization and electronic confinement, and with implications in the understanding of the distinct electronic behavior of Au layers and particles in the nm size range.