Surface Shubnikov-de Hass oscillations and non-zero Berry phases of the   topological hole conduction in Tl$_{1-x}$Bi$_{1+x}$Se$_2$
  We report the observation of two-dimensional Shubnikov-de Hass (SdH) oscillations in the topological insulator Tl$_{1-x}$Bi$_{1+x}$Se$_2$. Hall effect measurements exhibited electron-hole inversion in samples with bulk insulating properties. The SdH oscillations accompanying the hole conduction yielded a large surface carrier density of $n_{\rm{s}}=5.1 \times10^{12}$/cm$^2$, with the Landau-level fan diagram exhibiting the $\pi$ Berry phase. These results showed the electron-hole reversibility around the in-gap Dirac point and the hole conduction on the surface Dirac cone without involving the bulk metallic conduction. 
G. Eguchi, K. Kuroda, K. Shirai, A. Kimura, M. Shiraishi
cond-mat.mes-hall