Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 71: Electronic Structure of Surfaces I

O 71.8: Talk

Wednesday, March 18, 2020, 17:00–17:15, REC C 213

Surface electronic structure of Te on Ag(111) and Cu(111) — •Begmuhammet Geldiyev, Jonas Hauner, Janek Rieger, M. Alexander Schneider, and Thomas Fauster — Lehrstuhl für Festkörperphysik, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany

The unoccupied and occupied surface electronic structure of Te on Ag(111) and Cu(111) was studied by bichromatic two-photon photoemission (2PPE) and laser-based one-photon photoemission (1PPE). For 1/3 monolayer of Te a (√3 × √3)R30^∘ superstructure forms on Ag(111) in contrast to the (2√3 × √3)R30^∘ structure on Cu(111) with a doubled unit cell. For both surfaces two occupied bands are found by 1PPE and one unoccupied surface band by 2PPE. For Te/Cu(111) the higher-lying occupied band is split into two bands for the inequivalent directions of the doubled unit cell. All bands on Cu(111) are shifted up in energy compared to Ag(111) in agreement with density-functional-theory calculations. The orbital character of the electronic bands is probed by polarization-dependent measurements in normal emission. On Te/Ag(111) time-resolved 2PPE measurements yield a lifetime of ≈ 31 fs for the unoccupied state located ≈ 0.53 eV above the Fermi level, which has an electron-like dispersion. For the analogous surface state on Cu(111) at ≈ 1.43 eV no measureable lifetime was found.