Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 62: Posters: Surface Reactions and Dynamics, Nanostructures
O 62.7: Poster
Mittwoch, 2. April 2014, 17:30–21:00, P1
Electron dynamics of the topological insulator Sb2Te2S — •Sophia Ketterl1, Thomas Kunze1, 2, Thorsten U. Kampen2, Evgeny Chulkov3, and Martin Weinelt1 — 1FU Berlin, Germany — 2SPECS GmbH, Germany — 3UPV/EHU San Sebastian, Spain
The strength of the electron-phonon coupling in topological insulators is currently debated. Both strong and weak coupling constants have been reported [1,2].
We investigate the electron dynamics of the p-doped Sb2Te2S via time-resolved two-photon photoemission measurements with an angle-resolving time-of-flight spectrometer. p-doped Sb2Te2S exhibits a Dirac cone above the Fermi energy. In our experiment, the Dirac cone is populated by an infrared pump-pulse via direct absorption and interband scattering from the conduction band. In the Dirac cone we observe lifetimes on the picosecond timescale. The spectra hint at a stepwise relaxation via small-energy transfer processes. Cooling of the system leads to faster electron dynamics. This dynamics will be discussed in light of electron-electron and electron-phonon scattering.
[1] R. C. Hatch et. al., Phys. Rev. B 83, 241303 (2011).
[2] Z.-H. Pan et. al., Phys. Rev. Lett. 108, 187001 (2012).