Temperature-dependent terahertz conductivity of topological insulator Bi_1.5Sb_0.5Te_1.8Se_1.2

2012/06/06 by Chi Sin Tang, Tang, Chi Sin, Bin Xia +9
Physics and Astronomy · #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #cond-mat.mes-hall

paper · pdf · doi:10.48550/arxiv.1206.1122

5 pages, 5 figures

arxiv created 2012/06/06 · arxiv updated 2012/06/07

Abstract

Using Terahertz Time-Domain Spectroscopy, we study the temperature-dependent complex optical conductivity of the topological insulator, Bi_1.5Sb_0.5Te_1.8Se_1.2 single-crystal from 5 K to 150 K in the terahertz regime (0.4 -- 3.0 THz). We analyze our experimental results using the Drude-Lorentz model, with the Drude component representing the metallic surface state and the Lorentz term representing the bulk insulating state. We find the conductivity to be dominated by the Drude contribution, suggesting the presence of metallic surface states. The low-frequency real conductivity follows a thermally-activated behavior. Its origin is also discussed.

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