Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 51: Poster: Electronic Structure of Surfaces: Spectroscopy, Surface States

O 51.1: Poster

Dienstag, 13. März 2018, 18:15–20:30, Poster B

Unoccupied electronic structure of the giant Rashba system Bi/Ag(111) probed by two-photon photoemission — •Philipp Rosenzweig^1,2, Sebastian Otto¹, and Thomas Fauster¹ — ¹Lehrstuhl für Festkörperphysik, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstr. 7, D-91058 Erlangen, Germany — ²Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany

We probe the unoccupied band structure of the (√3×√3)R30^∘ substitutional surface alloy Bi/Ag(111)—from the Fermi to the vacuum level—by time- and angle-resolved, mono- and bichromatic, polarization-dependent two-photon photoemission (2PPE) at photon energies ranging from 1.51 to 4.89 eV. The obtained 2PPE patterns in ΓM direction are exceptionally rich in structure, revealing pronounced contributions from the Rashba-split sp_z and p_xp_y (m_j=1/2) initial states. The latter state is found to disperse downwards from (0.65± 0.03) eV above the Fermi level with a Rashba parameter of (3.0± 0.5) eVÅ—consistent with DFT calculations [1] and previous experiments [2, 3]; the corresponding lifetime is extracted as (26± 5) fs. The higher-lying, fully unoccupied p_xp_y (m_j=3/2) surface state can also be identified in remarkable agreement with theory [1]. Close to the vacuum level, the 2PPE patterns reveal signatures of three image-potential resonances and the unoccupied Ag bulk sp band.

[1] Bihlmayer et al., Phys. Rev. B 75, 195414 (2007).

[2] El-Kareh et al., Phys. Rev. Lett. 110, 176803 (2013).

[3] Wissing et al., Phys. Rev. Lett. 113, 116402 (2014).