Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 103: Topology and Symmetry Protected Materials I

O 103.4: Talk

Thursday, March 19, 2020, 11:15–11:30, WIL A317

Mid-infrared-pump terahertz-probe spectroscopy on the topological insulator (Bi_1−xSb_x)₂Te₃ — •Chris Reinhoffer¹, Andrea Bliesener¹, Gertjan Lippertz¹, Semyon Germanskiy¹, Yu Mukai^1,2, Yoichi Ando¹, Zhe Wang¹, and Paul H.M. van Loosdrecht¹ — ¹Institute of Physics II, University of Cologne, Cologne, Germany — ²Department of Electronic Science and Engineering, Kyoto University, Kyoto, Japan

(Bi_1−xSb_x)₂Te₃ is a series of topological insulators with the electronic properties tunable by varying the ratio between Bi and Sb. To get a better understanding of the inter-band scattering processes we performed mid-infrared-pump terahertz-probe spectroscopic measurements on three different (Bi_1−xSb_x)₂Te₃ compounds, in which the Fermi energy was chemically tuned by varying x to be in the conduction-, valence-band, and bulk bandgap, respectively. The non-equilibrium response was studied systematically for pump energies above and below the bandgap of 200 meV and as a function of temperature down to 5 K. Our measurements show evident differences in the pump-probe response in the different compounds, which are compared with different theoretical scenarios.