Experimental Realization of a Three-Dimensional Topological Insulator, Bi ₂ Te ₃

TLDR

Three-dimensional topological insulators are a new quantum state featuring a bulk gap and an odd number of relativistic Dirac fermions on the surface. Using angle‑resolved photoemission spectroscopy, the authors show that Bi₂Te₃ hosts a single nondegenerate Dirac cone, and hole doping can shift the Fermi level to intersect only surface states, revealing a full bulk gap. The study confirms Bi₂Te₃ as a simple model 3D topological insulator with a single Dirac cone and a large bulk gap, indicating promise for high‑temperature spintronics applications.

Abstract

Three-dimensional topological insulators are a new state of quantum matter with a bulk gap and odd number of relativistic Dirac fermions on the surface. By investigating the surface state of Bi2Te3 with angle-resolved photoemission spectroscopy, we demonstrate that the surface state consists of a single nondegenerate Dirac cone. Furthermore, with appropriate hole doping, the Fermi level can be tuned to intersect only the surface states, indicating a full energy gap for the bulk states. Our results establish that Bi2Te3 is a simple model system for the three-dimensional topological insulator with a single Dirac cone on the surface. The large bulk gap of Bi2Te3 also points to promising potential for high-temperature spintronics applications.