Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 55: Electronic Structure and Spin-Orbit Interaction II
O 55.12: Vortrag
Mittwoch, 13. März 2013, 18:45–19:00, H42
Electron dynamics of the topological insulator Bi2Te2Se — •Daniel Niesner1, Thomas Fauster1, Oleg Tereshchenko2, 4, Konstantin Kokh3, 4, and Evgueni Chulkov5 — 1Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7 A3, 91058 Erlangen — 2Institute of Semiconductor Physics, 630090 Novosibirsk, Russia — 3Institute of Geology and Mineralogy, 630090 Novosibirsk, Russia — 4Tomsk State University, 634050 Tomsk, Russia — 5Donostia International Physics Center (DIPC), 20018 San Sebastián/Donostia, Basque Country, Spain
In addition to the conventional Dirac cone, bismuth chalcogenides exhibit a high-lying topological surface state (TSS) in a projected bulk bandgap 1...1.5 eV above the Fermi level [1].
Bichromatic two-photon photoemission (2PPE, hν= 1.65 eV + 4.65 eV) was employed to follow the transient occupation of this state and the conduction band (CB*) above it. In addition, an image-potential state (IPS) is observed at a similar final-state energy. From a careful analysis of the polarization- and the time-dependence of the 2PPE data, the lifetimes of the single states are deconvolved. They amount to 25 fs (IPS), 22 fs (TSS) and 13 fs (CB*). Also, a linear energy-dependence of the decay rate of the conduction band below the TSS is found, as it is characteristic for layered materials [2].
[1] D. Niesner et al., Phys. Rev. B 86, 205403 (2012)
[2] S. Xu et al., Phys. Rev. Lett. 76, 483 (1996)