1202.1249 (R. Valdés Aguilar et al.)

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

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

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. We find no
evidence for a third spectral feature derived from topologically trivial
surface states.

View original: http://arxiv.org/abs/1202.1249