Surface Shubnikov-de Hass oscillations and non-zero Berry phases of the topological hole conduction in Tl$_{1-x}$Bi$_{1+x}$Se$_2$

TL;DR

This study observes two-dimensional Shubnikov-de Hass oscillations and non-zero Berry phases in the topological insulator Tl$_{1-x}$Bi$_{1+x}$Se$_2$, revealing surface hole conduction with electron-hole inversion and Berry phase characteristics.

Contribution

It reports the first observation of SdH oscillations with Berry phases in surface hole conduction of Tl$_{1-x}$Bi$_{1+x}$Se$_2$, highlighting electron-hole reversibility near the Dirac point.

Findings

Surface hole conduction with a large carrier density

Observation of $ ext{ extpi}$ Berry phase in SdH oscillations

Electron-hole inversion near the Dirac point

Abstract

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.