Persistence of Topological Order and Formation of Quantum Well States in Topological Insulators Bi2(Se,Te)3 under Ambient Conditions

TL;DR

This study investigates how topological surface states in Bi2(Se,Te)3 insulators behave under ambient conditions, revealing persistent topological order but significant surface modifications including quantum well state formation.

Contribution

It provides the first high-resolution ARPES analysis of topological insulators exposed to air, showing persistent topological order and formation of quantum well states dependent on composition.

Findings

Topological order persists after air exposure at room temperature.

Surface states are strongly modified, with quantum well states forming.

Formation of quantum well states depends on the material composition.

Abstract

The topological insulators represent a unique state of matter where the bulk is insulating with an energy gap while the surface is metallic with a Dirac cone protected by the time reversal symmetry. These characteristics provide a venue to explore novel quantum phenomena in fundamental physics and show potential applications in spintronics and quantum computing. One critical issue directly related with the applications as well as the fundamental studies is how the topological surface state will behave under ambient conditions (1 atmosphere air and room temperature). In this paper, we report high resolution angle-resolved photoemission measurements on the surface state of the prototypical topological insulators, Bi2Se3, Bi2Te3 and Bi2(Se0.4Te2.6), upon exposing to ambient conditions. We find that the topological order persists even when the surface is exposed to air at room temperature. However, the surface state is strongly modified after such an exposure. Particularly, we have observed the formation of two-dimensional quantum well states near the surface of the topological insulators after the exposure which depends sensitively on the original composition, x, in Bi2(Se3-xTex). These rich information are crucial in utilizing the surface state and in probing its physical properties under ambient conditions.