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Proceedings Paper

THz carrier dynamics and magnetotransport study of topological surface states in thin film Bi2Se3
Author(s): Varun S. Kamboj; Angadjit Singh; Thierry Ferrus; Harvey E. Beere; Liam B. Duffy; Thorsten Hesjedal; Crispin H. W. Barnes; David A. Ritchie
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Paper Abstract

The surface of a topological insulator harbors exotic topological states, protected against backscattering from disorder by time reversal symmetry. The study of these exotic quantum states not only provides an opportunity to explore fundamental phenomena in condensed matter physics, such as the spin Hall effect, but also lays the foundation for applications from quantum computing to spintronics. Conventional electrical measurements suffer from substantial bulk interference, making it difficult to clearly distinguish topological surface states from bulk states. Employing terahertz time-domain spectroscopy, we study the temperature-dependent optical behavior of a 23-quintuple-thick film of bismuth selenide (Bi2Se3) allowing for the deconvolution of the surface state response from the bulk. Our measurement of carrier dynamics give an optical mobility exceeding 2100 cm2/V•s at 4 K, indicative of a surface-dominated response, and a scattering lifetime of ~0.18 ps and a carrier density of 6×1012 cm-2 at 4 K for the Bi2Se3 film. The sample was further processed into a Hall bar device using two different etching techniques, a wet chemical etching and Ar+ ion milling, which resulting in a reduced Hall mobility. Even so, the magneto-conductance transport reveals weak antilocalization behavior in our Bi2Se3 sample, consistent with the presence of a single topological surface state mode.

Paper Details

Date Published: 23 February 2018
PDF: 10 pages
Proc. SPIE 10531, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XI, 105310I (23 February 2018); doi: 10.1117/12.2289116
Show Author Affiliations
Varun S. Kamboj, Univ. of Cambridge (United Kingdom)
Angadjit Singh, Univ. of Cambridge (United Kingdom)
Thierry Ferrus, Hitachi Cambridge Lab. (United Kingdom)
Harvey E. Beere, Univ. of Cambridge (United Kingdom)
Liam B. Duffy, Univ. of Oxford (United Kingdom)
Thorsten Hesjedal, Univ. of Oxford (United Kingdom)
Crispin H. W. Barnes, Univ of Cambridge (United Kingdom)
David A. Ritchie, Univ. of Cambridge (United Kingdom)

Published in SPIE Proceedings Vol. 10531:
Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XI
Laurence P. Sadwick; Tianxin Yang, Editor(s)

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