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Terahertz conductivity of topological surface states in Bi 1.5 Sb 0.5 Te 1.8 Se 1.2
Tang C.S.3; Xia B.3; Zou X.3; Chen S.3; Ou H.-W.1; Wang L.3; Rusydi A.1; Zhu J.-X.2; Chia E.E.M.3
2013-12-17
Source PublicationScientific Reports
ISSN20452322
Volume3
AbstractTopological 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 1.5 Sb 0.5 Te 1.7 Se 1.3 (BSTS) was found, showing high bulk resistivities of 1-10â.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 Bi 2 Se 3 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 30â.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.
DOI10.1038/srep03513
URLView the original
Language英語
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Cited Times [WOS]:40   [WOS Record]     [Related Records in WOS]
Document TypeJournal article
CollectionUniversity of Macau
Affiliation1.National University of Singapore
2.Los Alamos National Laboratory
3.Nanyang Technological University
Recommended Citation
GB/T 7714
Tang C.S.,Xia B.,Zou X.,et al. Terahertz conductivity of topological surface states in Bi 1.5 Sb 0.5 Te 1.8 Se 1.2[J]. Scientific Reports,2013,3.
APA Tang C.S..,Xia B..,Zou X..,Chen S..,Ou H.-W..,...&Chia E.E.M..(2013).Terahertz conductivity of topological surface states in Bi 1.5 Sb 0.5 Te 1.8 Se 1.2.Scientific Reports,3.
MLA Tang C.S.,et al."Terahertz conductivity of topological surface states in Bi 1.5 Sb 0.5 Te 1.8 Se 1.2".Scientific Reports 3(2013).
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