Electronic Structure of the Dark Surface of the Weak Topological Insulator Bi14Rh3I9
| Autor: | Markus Morgenstern, Marcus Liebmann, Klaus Koepernik, Jeroen van den Brink, Christian Pauly, Sergey Borisenko, Michael Ruck, Bertold Rasche, Manuel Richter |
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| Rok vydání: | 2016 |
| Předmět: |
Materials science
Photoemission spectroscopy Scanning tunneling spectroscopy Intermetallic Analytical chemistry General Physics and Astronomy 02 engineering and technology Electronic structure 01 natural sciences law.invention Condensed Matter::Materials Science symbols.namesake law 0103 physical sciences General Materials Science 010306 general physics Condensed matter physics Fermi level General Engineering 021001 nanoscience & nanotechnology Dipole Topological insulator symbols Condensed Matter::Strongly Correlated Electrons Scanning tunneling microscope 0210 nano-technology |
| Zdroj: | ACS Nano. 10:3995-4003 |
| ISSN: | 1936-086X 1936-0851 |
| DOI: | 10.1021/acsnano.6b00841 |
| Popis: | Compound Bi14Rh3I9 consists of ionic stacks of intermetallic [(Bi4Rh)3I](2+) and insulating [Bi2I8](2-) layers and has been identified to be a weak topological insulator. Scanning tunneling microscopy revealed the robust edge states at all step edges of the cationic layer as a topological fingerprint. However, these edge states are found 0.25 eV below the Fermi level, which is an obstacle for transport experiments. Here, we address this obstacle by comparing results of density functional slab calculations with scanning tunneling spectroscopy and angle-resolved photoemission spectroscopy. We show that the n-type doping of the intermetallic layer is intrinsically caused by the polar surface and is well-screened toward the bulk. In contrast, the anionic "spacer" layer shows a gap at the Fermi level, both on the surface and in the bulk; that is, it is not surface-doped due to iodine desorption. The well-screened surface dipole implies that a buried edge state, probably already below a single spacer layer, is located at the Fermi level. Consequently, a multilayer step covered by a spacer layer could provide access to the transport properties of the topological edge states. In addition, we find a lateral electronic modulation of the topologically nontrivial surface layer, which is traced back to the coupling with the underlying zigzag chain structure of the spacer layer. |
| Databáze: | OpenAIRE |
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