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arXiv · 1202.4029

Landau level spectroscopy of surface states in the topological insulator Bi$_{0.91}$Sb$_{0.09}$ via magneto-optics

A. A. Schafgans·A. A. Taskin·Yoichi Ando·Xiao-Liang Qi·B. C. Chapler·K. W. Post·D. N. Basov
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Abstract

We have performed broad-band zero-field and magneto-infrared spectroscopy of the three dimensional topological insulator Bi$_{0.91}$Sb$_{0.09}$. The zero-field results allow us to measure the value of the direct band gap between the conducting $L_a$ and valence $L_s$ bands. Under applied field in the Faraday geometry (\emph{k} $||$ \emph{H} $||$ C1), we measured the presence of a multitude of Landau level (LL) transitions, all with frequency dependence $\omega \propto \sqrt{H}$. We discuss the ramification of this observation for the surface and bulk properties of topological insulators.

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A. A. Schafgans, A. A. Taskin, Yoichi Ando, Xiao-Liang Qi, B. C. Chapler, K. W. Post, D. N. Basov. 2012-02-17. Landau level spectroscopy of surface states in the topological insulator Bi$_{0.91}$Sb$_{0.09}$ via magneto-optics. https://doi.org/10.1103/physrevb.85.239903

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