Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface

TL;DR

This paper reports the first observation and theoretical prediction of a large-gap topological insulator with a single spin-polarized Dirac cone on its surface, using Bi2Se3 materials, promising for quantum computing applications.

Contribution

It provides the first experimental observation and theoretical prediction of a large-gap topological insulator with a single Dirac cone in Bi2Se3, advancing quantum device research.

Findings

First observation of a single-surface-Dirac-cone in Bi2Se3

Theoretical predictions support experimental results

Undoped Bi2Se3 can serve as a topological quantum material

Abstract

Recent theories and experiments have suggested that strong spin-orbit coupling effects in certain band insulators can give rise to a new phase of quantum matter, the so-called topological insulator, which can show macroscopic entanglement effects. Such systems feature two-dimensional surface states whose electrodynamic properties are described not by the conventional Maxwell equations but rather by an attached axion field, originally proposed to describe strongly interacting particles. It has been proposed that a topological insulator with a single spin-textured Dirac cone interfaced with a superconductor can form the most elementary unit for performing fault-tolerant quantum computation. Here we present an angle-resolved photoemission spectroscopy study and first-principle theoretical calculation-predictions that reveal the first observation of such a topological state of matter featuring a single-surface-Dirac-cone realized in the naturally occurring Bi$_2$Se$_3$ class of materials. Our results, supported by our theoretical predictions and calculations, demonstrate that undoped compound of this class of materials can serve as the parent matrix compound for the long-sought topological device where in-plane surface carrier transport would have a purely quantum topological origin. Our study further suggests that the undoped compound reached via n-to-p doping should show topological transport phenomena even at room temperature.