Probing embedded topological modes in bulk-like GeTe-Sb 2 Te 3 heterostructures
Koenraad, Paul M.
Nature Publishing Group UK
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Nakamura, H., Hofmann, J., Inoue, N., Koelling, S., Koenraad, P. M., Mussler, G., Grützmacher, D., & et al. (2020). Probing embedded topological modes in bulk-like GeTe-Sb 2 Te 3 heterostructures. Scientific Reports, 10 (1)https://doi.org/10.1038/s41598-020-76885-7
Funder: Core Research for Evolutional Science and Technology; doi: http://dx.doi.org/10.13039/501100003382
Funder: Engineering and Physical Sciences Research Council; doi: http://dx.doi.org/10.13039/501100000266
Abstract: The interface between topological and normal insulators hosts metallic states that appear due to the change in band topology. While topological states at a surface, i.e., a topological insulator-air/vacuum interface, have been studied intensely, topological states at a solid-solid interface have been less explored. Here we combine experiment and theory to study such embedded topological states (ETSs) in heterostructures of GeTe (normal insulator) and Sb2Te3 (topological insulator). We analyse their dependence on the interface and their confinement characteristics. First, to characterise the heterostructures, we evaluate the GeTe-Sb2Te3 band offset using X-ray photoemission spectroscopy, and chart the elemental composition using atom probe tomography. We then use first-principles to independently calculate the band offset and also parametrise the band structure within a four-band continuum model. Our analysis reveals, strikingly, that under realistic conditions, the interfacial topological modes are delocalised over many lattice spacings. In addition, the first-principles calculations indicate that the ETSs are relatively robust to disorder and this may have practical ramifications. Our study provides insights into how to manipulate topological modes in heterostructures and also provides a basis for recent experimental findings [Nguyen et al. Sci. Rep. 6, 27716 (2016)] where ETSs were seen to couple over thick layers.
Article, /639/766/119/2792/4128, /639/766/119/995, /639/766/119/544, article
External DOI: https://doi.org/10.1038/s41598-020-76885-7
This record's URL: https://www.repository.cam.ac.uk/handle/1810/315012
Attribution 4.0 International (CC BY 4.0)
Licence URL: https://creativecommons.org/licenses/by/4.0/