Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Proc Natl Acad Sci U S A. 2012 Mar 6;109(10):3694-8. doi: 10.1073/pnas.1115555109. Epub 2012 Feb 21.
The physical property investigation (like transport measurements) and ultimate application of the topological insulators usually involve surfaces that are exposed to ambient environment (1 atm and room temperature). One critical issue is how the topological surface state will behave under such ambient conditions. We report high resolution angle-resolved photoemission measurements to directly probe the surface state of the prototypical topological insulators, Bi(2)Se(3) and Bi(2)Te(3), upon exposing to various environments. We find that the topological order is robust 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 exposed surface of the topological insulators. These findings provide key information in understanding the surface properties of the topological insulators under ambient environment and in engineering the topological surface state for applications.
物理性质研究（如输运测量）和拓扑绝缘体的最终应用通常涉及暴露于环境（1 个大气压和室温）的表面。一个关键问题是拓扑表面态在这种环境条件下将如何表现。我们报告了高分辨率角分辨光发射测量，以直接探测原型拓扑绝缘体 Bi(2)Se(3)和 Bi(2)Te(3)在暴露于各种环境时的表面态。我们发现，即使表面在室温下暴露于空气中，拓扑序也很稳定。然而，表面态在暴露后会发生强烈的改变。特别是，我们观察到在拓扑绝缘体的暴露表面附近形成了二维量子阱态。这些发现为理解拓扑绝缘体在环境中的表面性质以及为应用工程拓扑表面态提供了关键信息。
