Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)
O 58.28: Poster
Mittwoch, 13. März 2013, 18:15–21:45, Poster B1
Unoccupied surface states of p-type topological insulators — •Volker Hermann1, Daniel Niesner1, Thomas Fauster1, Eugene V. Chulkov2, Ziya S. Aliev3, Mahammad B. Babanly3, and Imamaddin R. Amiraslanov4 — 1Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen, Germany — 2Donostia International PhysicsCenter (DIPC), 20018 San Sebastián/Donostia, Basque Country, Spain — 3General and Inorganic Chemistry Department, Baku State University, Baku, AZ1148, Azerbaijan — 4Institute of Physics, Azerbaijan National Academy of Science, Baku, AZ1143, Azerbaijan
Density functional theory calculations predict a topological surface state (TSS) for SnSb2Te4 [1]. No Dirac point was found in UV photoemission. The material therefore is doped p-type.
Two-photon photoemission was used to investigate the unoccupied band structure. The Dirac point is found 0.3 eV above the Fermi level with a group velocity of 3.4 eVÅ. A work function of about 5.25 eV was measured. Time-resolved experiments show that the TSS is not only populated optically by the pump pulse but also indirectly by refilling from the bulk conduction band similar to the case of Bi2Se3 [2]. From a rate-equation model a lifetime of about 45 fs was found. A small lifetime is explained by scattering to the partly depleted bulk valence band.
[1] T.V. Menshchikova et al, Appl. Surf. Sci., in press
[2] J.A. Sobota et al., Phys. Rev. Lett. 108, 117403 (2012)