Large Gap Topological Insulator Bi2Te3 with a Single Dirac Cone on the Surface

TL;DR

This study confirms that Bi2Te3 is a three-dimensional topological insulator featuring a single Dirac cone on its surface, achieved through ARPES and transport measurements, and tuning the Fermi level via doping.

Contribution

First experimental demonstration that Bi2Te3 has a single Dirac cone surface state, validating theoretical predictions of its topological insulator nature.

Findings

Surface state consists of a single non-degenerate Dirac cone

Fermi level can be tuned to intersect only surface states with doping

Bulk states exhibit a full energy gap when Fermi level is tuned

Abstract

We investigate the surface state of Bi$_2$Te$_3$ using angle resolved photoemission spectroscopy (ARPES) and transport measurements. By scanning over the entire Brillouin zone (BZ), we demonstrate that the surface state consists of a single non-degenerate Dirac cone centered at the $\Gamma$ point. Furthermore, with appropriate hole (Sn) doping to counteract intrinsic n-type doping from vacancy and anti-site defects, the Fermi level can be tuned to intersect only the surface states, indicating a full energy gap for the bulk states, consistent with a carrier sign change near this doping in transport properties. Our experimental results establish for the first time that Bi$_2$Te$_3$ is a three dimensional topological insulator with a single Dirac cone on the surface, as predicted by a recent theory.