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arXiv · 2004.13565

Landau level spectroscopy of Bi$_2$Te$_3$

I. Mohelsky·A. Dubroka·J. Wyzula·A. Slobodeniuk·G. Martinez·Y. Krupko·B. A. Piot·O. Caha·J. Humlicek·G. Bauer·G. Springholz·M. Orlita
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Abstract

Here we report on Landau level spectroscopy in magnetic fields up to 34 T performed on a thin film of topological insulator Bi$_2$Te$_3$ epitaxially grown on a BaF$_2$ substrate. The observed response is consistent with the picture of a direct-gap semiconductor in which charge carriers closely resemble massive Dirac particles. The fundamental band gap reaches $E_g=(175\pm 5)$~meV at low temperatures and it is not located on the trigonal axis, thus displaying either six or twelvefold valley degeneracy. Notably, our magneto-optical data do not indicate any band inversion. This suggests that the fundamental band gap is relatively distant from the $\Gamma$ point where profound inversion exists andgives rise to relativistic-like surface states of Bi$_2$Te$_3$.

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I. Mohelsky, A. Dubroka, J. Wyzula, A. Slobodeniuk, G. Martinez, Y. Krupko, B. A. Piot, O. Caha, J. Humlicek, G. Bauer, G. Springholz, M. Orlita. 2020-04-28. Landau level spectroscopy of Bi$_2$Te$_3$. https://doi.org/10.1103/physrevb.102.085201

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