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arXiv · 1202.1249

Aging and reduced bulk conductance in thin films of the topological insulator Bi$_2$Se$_3$

R. Valdés Aguilar·L. Wu·A. V. Stier·L. S. Bilbro·M. Brahlek·N. Bansal·S. Oh·N. P. Armitage
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Abstract

We report on the effect of exposure to atmospheric conditions on the THz conductivity of thin films of the topological insulator Bi$_2$Se$_3$. We find: 1) two contributions of mobile charge carriers to the THz conductivity immediately after growth, and 2) the spectral weight of the smaller of these decays significantly over a period of several days as the film is exposed to ambient conditions, while the other remains relatively constant. We associate the former with a bulk response, and the latter with the surface. The surface response exhibits the expected robustness of the carriers from 2D topological surface states. We find no evidence for a third spectral feature derived from topologically trivial surface states.

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R. Valdés Aguilar, L. Wu, A. V. Stier, L. S. Bilbro, M. Brahlek, N. Bansal, S. Oh, N. P. Armitage. 2012-02-06. Aging and reduced bulk conductance in thin films of the topological insulator Bi$_2$Se$_3$. https://doi.org/10.1063/1.4801911

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