Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 66: Electronic Structure of Surfaces

O 66.13: Poster

Mittwoch, 18. März 2015, 18:15–21:00, Poster A

Two-photon photoemission from GeSb₂Te₄ — •Sebastian Otto, Philipp Rosenzweig, and Thomas Fauster — Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany

Time- and angle-resolved, polarization-dependent two-photon photoemission is used to study the electronic structure and dynamics at the surface of GeSb₂Te₄. The topological surface state is centered at 0.45 eV above the Fermi level due to intrinsic p-doping. The valence band, the two lowest conduction bands and an image-potential state are identified. Measurements with circularly polarized light show the expected change of sign in the circular-dichroism asymmetry at the Dirac point. The dichroism depends only on the circular polarization of the probe pulse, which indicates an indirect filling from the conduction band. The second conduction band shows a negative dispersion similar to SnSb₂Te₄ [1] and Sb₂Te₃ [2].
[1] D. Niesner, S. Otto, V. Hermann and Th. Fauster, Phys. Rev. B 89, 081404(R) (2014)
[2] J. Reimann, J. Güdde, K. Kuroda, E. V. Chulkov and U. Höfer, Phys. Rev. B 90, 081106(R) (2014)