Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 80: Surface Dynamics I

O 80.6: Talk

Thursday, April 3, 2014, 17:15–17:30, GER 38

Time- and angle-resolved 2PPE of unoccupied electronic states of topological insulators Sb₂Te₃ and Sb₂Te₂S — •Johannes Reimann, Jens Güdde, and Ulrich Höfer — Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität, D-35032 Marburg

Topological insulators with their unique protected surface state offer promising potentials for a wide field of applications. In order to make use of the conducting properties of the surface state it is important to know the properties of both the occupied and the unoccupied electronic states close to the Fermi-energy.

In this work the unoccupied electronic states of the topological insulators Sb₂Te₃ and Sb₂Te₂S have been investigated by time- and angle-resolved two-photon photoemission (2PPE) along Γ-K- and Γ-M-direction. Both materials show a linear dispersive electronic state near Fermi-energy, resembling the typical Dirac-Cone structure. Additional bulk and surface states at higher energies can be identified. The experimental spectroscopic results will be compared with theoretical calculations of the surface and bulk band structure. First results on the electron-dynamics using time- and angle-resolved 2PPE are presented. While both materials show similar dynamics at room temperature, the dynamics at low temperatures differs.