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Topological delocalization and tuning of surface channel separation in Bi(2)Se(2)Te Topological Insulator Thin films

The surface states of a 3D topological insulator (TI) exhibit topological protection against backscattering. However, the contribution of bulk electrons to the transport data is an impediment to the topological protection of surface states. We report the tuning of the chemical potential in the bulk...

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Autores principales: Gopal, Radha Krishna, Singh, Sourabh, Mandal, Arpita, Sarkar, Jit, Mitra, Chiranjib
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5501793/
https://www.ncbi.nlm.nih.gov/pubmed/28687773
http://dx.doi.org/10.1038/s41598-017-04458-2
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author Gopal, Radha Krishna
Singh, Sourabh
Mandal, Arpita
Sarkar, Jit
Mitra, Chiranjib
author_facet Gopal, Radha Krishna
Singh, Sourabh
Mandal, Arpita
Sarkar, Jit
Mitra, Chiranjib
author_sort Gopal, Radha Krishna
collection PubMed
description The surface states of a 3D topological insulator (TI) exhibit topological protection against backscattering. However, the contribution of bulk electrons to the transport data is an impediment to the topological protection of surface states. We report the tuning of the chemical potential in the bulk in Bi(2)Se(2)Te TI thin films, pinning it near the center of the bulk band gap, thereby suppressing the bulk carriers. The temperature dependent resistance of these films show activated behavior down to 50 K, followed by a metallic transition at lower temperatures, a hallmark of robustness of TI surface states. Manifestation of topological protection and surface dominated transport is explained by 2D weak antilocalization phenomenon. We further explore the effect of surface to bulk coupling in TI in this work, which is captured by the number of effective conducting surface channels that participate in the transport. The presence of a single conducting channel indicates a strong surface to bulk coupling which is detrimental to purely topological transport. We demonstrate the decoupling of topological surface states on opposite surfaces of thin films, thereby suppressing the bulk transport. Our findings provide a deeper understanding of surface to bulk coupling along with topological transport behavior and their respective tunability.
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spelling pubmed-55017932017-07-10 Topological delocalization and tuning of surface channel separation in Bi(2)Se(2)Te Topological Insulator Thin films Gopal, Radha Krishna Singh, Sourabh Mandal, Arpita Sarkar, Jit Mitra, Chiranjib Sci Rep Article The surface states of a 3D topological insulator (TI) exhibit topological protection against backscattering. However, the contribution of bulk electrons to the transport data is an impediment to the topological protection of surface states. We report the tuning of the chemical potential in the bulk in Bi(2)Se(2)Te TI thin films, pinning it near the center of the bulk band gap, thereby suppressing the bulk carriers. The temperature dependent resistance of these films show activated behavior down to 50 K, followed by a metallic transition at lower temperatures, a hallmark of robustness of TI surface states. Manifestation of topological protection and surface dominated transport is explained by 2D weak antilocalization phenomenon. We further explore the effect of surface to bulk coupling in TI in this work, which is captured by the number of effective conducting surface channels that participate in the transport. The presence of a single conducting channel indicates a strong surface to bulk coupling which is detrimental to purely topological transport. We demonstrate the decoupling of topological surface states on opposite surfaces of thin films, thereby suppressing the bulk transport. Our findings provide a deeper understanding of surface to bulk coupling along with topological transport behavior and their respective tunability. Nature Publishing Group UK 2017-07-07 /pmc/articles/PMC5501793/ /pubmed/28687773 http://dx.doi.org/10.1038/s41598-017-04458-2 Text en © The Author(s) 2017 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Gopal, Radha Krishna
Singh, Sourabh
Mandal, Arpita
Sarkar, Jit
Mitra, Chiranjib
Topological delocalization and tuning of surface channel separation in Bi(2)Se(2)Te Topological Insulator Thin films
title Topological delocalization and tuning of surface channel separation in Bi(2)Se(2)Te Topological Insulator Thin films
title_full Topological delocalization and tuning of surface channel separation in Bi(2)Se(2)Te Topological Insulator Thin films
title_fullStr Topological delocalization and tuning of surface channel separation in Bi(2)Se(2)Te Topological Insulator Thin films
title_full_unstemmed Topological delocalization and tuning of surface channel separation in Bi(2)Se(2)Te Topological Insulator Thin films
title_short Topological delocalization and tuning of surface channel separation in Bi(2)Se(2)Te Topological Insulator Thin films
title_sort topological delocalization and tuning of surface channel separation in bi(2)se(2)te topological insulator thin films
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5501793/
https://www.ncbi.nlm.nih.gov/pubmed/28687773
http://dx.doi.org/10.1038/s41598-017-04458-2
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