Terahertz conductivity of topological surface states in Bi1.5Sb0.5Te1.8Se1.2
Topological insulators are electronic materials with an insulating bulk and conducting surface. However, due to free carriers in the bulk, the properties of the metallic surface are difficult to detect and characterize in most topological insulator materials. Recently, a new topological insulator Bi...
Saved in:
Main Authors: | , , , , , , , , |
---|---|
Other Authors: | |
Format: | Article |
Language: | English |
Published: |
2014
|
Subjects: | |
Online Access: | https://hdl.handle.net/10356/100919 http://hdl.handle.net/10220/18597 |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Institution: | Nanyang Technological University |
Language: | English |
id |
sg-ntu-dr.10356-100919 |
---|---|
record_format |
dspace |
spelling |
sg-ntu-dr.10356-1009192023-02-28T19:21:11Z Terahertz conductivity of topological surface states in Bi1.5Sb0.5Te1.8Se1.2 Tang, Chi Sin Xia, Bin Zou, Xingquan Chen, Shi Ou, Hong-Wei Wang, Lan Rusydi, A. Zhu, Jian-Xin Chia, Elbert E. M. School of Physical and Mathematical Sciences DRNTU::Science::Chemistry::Biochemistry::Spectroscopy Topological insulators are electronic materials with an insulating bulk and conducting surface. However, due to free carriers in the bulk, the properties of the metallic surface are difficult to detect and characterize in most topological insulator materials. Recently, a new topological insulator Bi1.5Sb0.5Te1.7Se1.3 (BSTS) was found, showing high bulk resistivities of 1–10 Ω.cm and greater contrast between the bulk and surface resistivities compared to other Bi-based topological insulators. Using Terahertz Time-Domain Spectroscopy (THz-TDS), we present complex conductivity of BSTS single crystals, disentangling the surface and bulk contributions. We find that the Drude spectral weight is 1–2 orders of magnitude smaller than in other Bi-based topological insulators, and similar to that of Bi2Se3 thin films, suggesting a significant contribution of the topological surface states to the conductivity of the BSTS sample. Moreover, an impurity band is present about 30 meV below the Fermi level, and the surface and bulk carrier densities agree with those obtained from transport data. Furthermore, from the surface Drude contribution, we obtain a ~98% transmission through one surface layer — this is consistent with the transmission through single-layer or bilayer graphene, which shares a common Dirac-cone feature in the band structure. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Published version 2014-01-15T07:16:27Z 2019-12-06T20:30:42Z 2014-01-15T07:16:27Z 2019-12-06T20:30:42Z 2013 2013 Journal Article Tang, C. S., Xia, B., Zou, X., Chen, S., Ou, H.-W., Wang, L., et al. (2013). Terahertz conductivity of topological surface states in Bi1.5Sb0.5Te1.8Se1.2. Scientific Reports, 3, 3513. 2045-2322 https://hdl.handle.net/10356/100919 http://hdl.handle.net/10220/18597 10.1038/srep03513 24343202 en Scientific reports © 2013 The Author(s) (Nature Publishing Group) This paper was published in Scientific Reports and is made available as an electronic reprint (preprint) with permission of The Author(s). The paper can be found at the following official DOI: doi:http://dx.doi.org/10.1038/srep03513. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law. 6 p. application/pdf |
institution |
Nanyang Technological University |
building |
NTU Library |
continent |
Asia |
country |
Singapore Singapore |
content_provider |
NTU Library |
collection |
DR-NTU |
language |
English |
topic |
DRNTU::Science::Chemistry::Biochemistry::Spectroscopy |
spellingShingle |
DRNTU::Science::Chemistry::Biochemistry::Spectroscopy Tang, Chi Sin Xia, Bin Zou, Xingquan Chen, Shi Ou, Hong-Wei Wang, Lan Rusydi, A. Zhu, Jian-Xin Chia, Elbert E. M. Terahertz conductivity of topological surface states in Bi1.5Sb0.5Te1.8Se1.2 |
description |
Topological insulators are electronic materials with an insulating bulk and conducting surface. However, due to free carriers in the bulk, the properties of the metallic surface are difficult to detect and characterize in most topological insulator materials. Recently, a new topological insulator Bi1.5Sb0.5Te1.7Se1.3 (BSTS) was found, showing high bulk resistivities of 1–10 Ω.cm and greater contrast between the bulk and surface resistivities compared to other Bi-based topological insulators. Using Terahertz Time-Domain Spectroscopy (THz-TDS), we present complex conductivity of BSTS single crystals, disentangling the surface and bulk contributions. We find that the Drude spectral weight is 1–2 orders of magnitude smaller than in other Bi-based topological insulators, and similar to that of Bi2Se3 thin films, suggesting a significant contribution of the topological surface states to the conductivity of the BSTS sample. Moreover, an impurity band is present about 30 meV below the Fermi level, and the surface and bulk carrier densities agree with those obtained from transport data. Furthermore, from the surface Drude contribution, we obtain a ~98% transmission through one surface layer — this is consistent with the transmission through single-layer or bilayer graphene, which shares a common Dirac-cone feature in the band structure. |
author2 |
School of Physical and Mathematical Sciences |
author_facet |
School of Physical and Mathematical Sciences Tang, Chi Sin Xia, Bin Zou, Xingquan Chen, Shi Ou, Hong-Wei Wang, Lan Rusydi, A. Zhu, Jian-Xin Chia, Elbert E. M. |
format |
Article |
author |
Tang, Chi Sin Xia, Bin Zou, Xingquan Chen, Shi Ou, Hong-Wei Wang, Lan Rusydi, A. Zhu, Jian-Xin Chia, Elbert E. M. |
author_sort |
Tang, Chi Sin |
title |
Terahertz conductivity of topological surface states in Bi1.5Sb0.5Te1.8Se1.2 |
title_short |
Terahertz conductivity of topological surface states in Bi1.5Sb0.5Te1.8Se1.2 |
title_full |
Terahertz conductivity of topological surface states in Bi1.5Sb0.5Te1.8Se1.2 |
title_fullStr |
Terahertz conductivity of topological surface states in Bi1.5Sb0.5Te1.8Se1.2 |
title_full_unstemmed |
Terahertz conductivity of topological surface states in Bi1.5Sb0.5Te1.8Se1.2 |
title_sort |
terahertz conductivity of topological surface states in bi1.5sb0.5te1.8se1.2 |
publishDate |
2014 |
url |
https://hdl.handle.net/10356/100919 http://hdl.handle.net/10220/18597 |
_version_ |
1759857941613117440 |