Imaging current distribution in a topological insulator Bi2Se3 in the presence of competing surface and bulk contributions to conductivity

Abstract Two-dimensional (2D) topological surface states in a three-dimensional topological insulator (TI) should produce uniform 2D surface current distribution. However, our transport current imaging studies on Bi2Se3 thin film reveal non-uniform current sheet flow at 15 K with strong edge current...

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Autores principales:	Amit Jash, Ankit Kumar, Sayantan Ghosh, A. Bharathi, S. S. Banerjee
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/2fe1dc8fee054417bf9fb73106b32c33
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spelling	oai:doaj.org-article:2fe1dc8fee054417bf9fb73106b32c332021-12-02T13:27:08ZImaging current distribution in a topological insulator Bi2Se3 in the presence of competing surface and bulk contributions to conductivity10.1038/s41598-021-86706-02045-2322https://doaj.org/article/2fe1dc8fee054417bf9fb73106b32c332021-04-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-86706-0https://doaj.org/toc/2045-2322Abstract Two-dimensional (2D) topological surface states in a three-dimensional topological insulator (TI) should produce uniform 2D surface current distribution. However, our transport current imaging studies on Bi2Se3 thin film reveal non-uniform current sheet flow at 15 K with strong edge current flow. This is consistent with other imaging studies on thin films of Bi2Se3. In contrast to strong edge current flow in thin films, in single crystal of Bi2Se3 at 15 K our current imaging studies show the presence of 3.6 nm thick uniform 2D sheet current flow. Above 70 K, this uniform 2D sheet current sheet begins to disintegrate into a spatially non-uniform flow. The flow becomes patchy with regions having high and low current density. The area fraction of the patches with high current density rapidly decreases at temperatures above 70 K, with a temperature dependence of the form $$1/\left\| {T - 70} \right\|^{0.35}$$ 1 / T - 70 0.35 . The temperature scale of 70 K coincides with the onset of bulk conductivity in the crystal due to electron doping by selenium vacancy clusters in Bi2Se3. Thus our results show a temperature dependent competition between surface and bulk conductivity produces a temperature dependent variation in uniformity of current flow in the topological insulator.Amit JashAnkit KumarSayantan GhoshA. BharathiS. S. BanerjeeNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-9 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Amit Jash Ankit Kumar Sayantan Ghosh A. Bharathi S. S. Banerjee Imaging current distribution in a topological insulator Bi2Se3 in the presence of competing surface and bulk contributions to conductivity
description	Abstract Two-dimensional (2D) topological surface states in a three-dimensional topological insulator (TI) should produce uniform 2D surface current distribution. However, our transport current imaging studies on Bi2Se3 thin film reveal non-uniform current sheet flow at 15 K with strong edge current flow. This is consistent with other imaging studies on thin films of Bi2Se3. In contrast to strong edge current flow in thin films, in single crystal of Bi2Se3 at 15 K our current imaging studies show the presence of 3.6 nm thick uniform 2D sheet current flow. Above 70 K, this uniform 2D sheet current sheet begins to disintegrate into a spatially non-uniform flow. The flow becomes patchy with regions having high and low current density. The area fraction of the patches with high current density rapidly decreases at temperatures above 70 K, with a temperature dependence of the form $$1/\left\| {T - 70} \right\|^{0.35}$$ 1 / T - 70 0.35 . The temperature scale of 70 K coincides with the onset of bulk conductivity in the crystal due to electron doping by selenium vacancy clusters in Bi2Se3. Thus our results show a temperature dependent competition between surface and bulk conductivity produces a temperature dependent variation in uniformity of current flow in the topological insulator.
format	article
author	Amit Jash Ankit Kumar Sayantan Ghosh A. Bharathi S. S. Banerjee
author_facet	Amit Jash Ankit Kumar Sayantan Ghosh A. Bharathi S. S. Banerjee
author_sort	Amit Jash
title	Imaging current distribution in a topological insulator Bi2Se3 in the presence of competing surface and bulk contributions to conductivity
title_short	Imaging current distribution in a topological insulator Bi2Se3 in the presence of competing surface and bulk contributions to conductivity
title_full	Imaging current distribution in a topological insulator Bi2Se3 in the presence of competing surface and bulk contributions to conductivity
title_fullStr	Imaging current distribution in a topological insulator Bi2Se3 in the presence of competing surface and bulk contributions to conductivity
title_full_unstemmed	Imaging current distribution in a topological insulator Bi2Se3 in the presence of competing surface and bulk contributions to conductivity
title_sort	imaging current distribution in a topological insulator bi2se3 in the presence of competing surface and bulk contributions to conductivity
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/2fe1dc8fee054417bf9fb73106b32c33
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Imaging current distribution in a topological insulator Bi2Se3 in the presence of competing surface and bulk contributions to conductivity

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