School of Physical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
Nanoscale. 2019 Feb 21;11(8):3591-3598. doi: 10.1039/c8nr09760g.
We report the formation of a nonlayered tellurene monolayer in its alpha-phase through an anisotropic ultrasonication method. The nonlayered tellurene has so far been predicted to exhibit a topologically insulating state of matter in two-dimensional (2D) form with an insulating interior and metallic edge states propagating along the perimeter of the 2D objects. In this work, we report direct evidence of elemental topological insulator behavior in the material through a localized mode of measurement, that is, scanning tunneling spectroscopic studies. We moreover deliberate on the length scale the time-reversal symmetry-protected edge states extend towards the interior. The metallic edge, which has been found to span over a 3 nm region, opens and widens monotonically into gapped states. The appearance of the elemental 2D topological insulator phase has been explained in terms of built-in strains in the systems as viewed through a shift in the Raman modes.
我们通过各向异性超声方法报告了非层状碲烯单层在其α相中的形成。到目前为止，人们一直预测，在二维（2D）形式中，非层状碲烯将表现出拓扑绝缘物质的状态，其内部绝缘，边缘金属态沿着二维物体的周长传播。在这项工作中，我们通过局部测量模式，即扫描隧道光谱研究，报告了该材料中元素拓扑绝缘体行为的直接证据。此外，我们还详细讨论了时间反演对称性保护的边缘态向内部延伸的长度尺度。已经发现金属边缘跨越 3nm 区域，单调地打开并扩展到带隙状态。通过拉曼模式的位移，可以看出系统中的内置应变，从而解释了这种元素二维拓扑绝缘体相的出现。
