Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 116: Topological insulators (organized by MA)

HL 116.3: Vortrag

Freitag, 4. April 2014, 10:00–10:15, HSZ 04

Combined STM/STS- and ARPES-investigation of the quaternary Topological Insulator Bi1.5Sb0.5Te1.8Se1.2 — •Thomas Bathon1, Felix Reis1, Christoph Seibel2, Hendrik Bentmann2, Paolo Sessi1, Friedrich Reinert2, and Matthias Bode11Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany — 2Physikalisches Institut, Experimentelle Physik VII, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany

We present a combined scanning tunneling microscopy/spectroscopy (STM/STS) and angular-resolved photoemission spectroscopy (ARPES) characterization of the electronic properties of the quaternary compound Bi1.5Sb0.5Te1.8Se1.2. ARPES-data evidence that this compound is still a Topological Insulator (TI) with a single Dirac cone, which is characteristic for the Bi2X3-class. The topological properties of the surface state, i.e. forbidden backscattering, have been confirmed by Fourier-transformed differential conductance (dI/dU) maps. Measurements performed both above and below the Fermi level allow us to determine the energy dispersion relation, the carrier velocity, and—by extrapolation to zero momentum—the position of the Dirac point. The observed scattering vectors are not as well-defined as those observed in binary compounds, probably due to substitutional disorder which results in a spatial fluctuation of the chemical potential. Our investigations illustrate how the properties of the well-known TI Bi2Te3 can be changed by chemical substitution.

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