Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 103: Transport: Poster Session

TT 103.40: Poster

Donnerstag, 19. März 2015, 15:00–18:00, Poster B

THz magneto-optics and FIR spectroscopy on topological insulators — •Nick Borgwardt¹, Gregor Mussler², Malte Langenbach¹, Joachim Hemberger¹, and Markus Grüninger¹ — ¹1 II. Physikalisches Institut, Universität zu Köln, Cologne, Germany — ²Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Germany

Topological insulators are one of the most discussed areas of current research in condensed matter physics. Topological insulators show outstanding electromagnetic properties. One example is the Faraday rotation angle, which in the quantum Hall state is expected to be given by the fine structure constant. We report on optical data in the THz and FIR range measured on thin films of (Bi,Sb)2Te3 grown on high-resistive Si (111) wafers by MBE. For magneto-optical measurements in the THz range, we employ two photomixers placed inside a magneto-cryostat with magnetic fields B of up to 8T. Phase-sensitive detection of circularly polarized light allows for a direct determination of the Faraday rotation angle without any mechanically moving components in the THz path. We studied the transmittance and phase change as a function of temperature and magnetic field for thin films of various thicknesses.