Dresden 2014 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 42: Topological insulators (organized by O)
HL 42.8: Talk
Tuesday, April 1, 2014, 12:15–12:30, GER 38
The edge state at the dark side of the weak topological insulator Bi14Rh3I9 probed by STM — •Christian Pauly1, Bertold Rasche2, Marcus Liebmann1, Marco Pratzer1, Klaus Koepernik3, Manuel Richter3, Michael Ruck2, Jeroen van den Brink3, and Markus Morgenstern1 — 1II. Institute of Physics B, RWTH Aachen University and Jara Fit, Germany — 2Departement of Chemistry and Food Chemistry, TU Dresden, Germany — 3Institute for Theoretical Solid State Physics, IFW Dresden, Germany
Using scanning tunneling microscopy (STM) and spectroscopy (STS) at 6 K, we probe the local atomic and electronic structure of the weak topological insulator Bi14Rh3I9 [1]. In [001]-direction, the material is built from stacks of intermetallic planes with non-trivial 2D topology and spacer layers in between. Thus, the surfaces of the intermetallic planes, which are the natural cleaving planes of the material, exhibit a trivial band gap however with topologically protected states at each step edge [1]. Bi14Rh3I9 is cleaved at a base pressure of 10−10 mbar giving rise to several hundreds of nm large terraces of the intermetallic layer interrupted by step edges. Using STS, we identified the band gap on top of the intermetallic layer, which is in agreement with ARPES data, whereas at the step edges we directly mapped the edge state. The edge state appears continuously through the band gap and exhibits a spatial distribution of 0.4 nm FWHM. The observed spatial periodicity along the step edge is in line with the atomic structure confirming the Bloch type of this state. Partially, dispersive features appear which will be discussed. [1] B. Rasche et al., Nature Mater. 12, 422 (2013)