Making a large-gap topological insulator Although of interest to basic research, topological insulators (TIs) have not yet lived up to their technological potential. This is partly because their protected surface-edge state usually lives within a narrow energy gap, with its exotic transport properties overwhelmed by the ordinary bulk material. Reis et al. show that a judicious choice of materials can make the gap wide enough for the topological properties to be apparent at room temperature. Numerical calculations indicate that a monolayer of Bismuth grown on SiC(0001) is a two-dimensional TI with a large energy gap. The researchers fabricated such a heterostructure and characterized it using scanning tunneling spectroscopy. The size of the experimentally measured gap was consistent with the calculations. Science, this issue p. 287 Scanning tunneling spectroscopy indicates a large energy gap and conducting edge states, consistent with calculations. Quantum spin Hall materials hold the promise of revolutionary devices with dissipationless spin currents but have required cryogenic temperatures owing to small energy gaps. Here we show theoretically that a room-temperature regime with a large energy gap may be achievable within a paradigm that exploits the atomic spin-orbit coupling. The concept is based on a substrate-supported monolayer of a high–atomic number element and is experimentally realized as a bismuth honeycomb lattice on top of the insulating silicon carbide substrate SiC(0001). Using scanning tunneling spectroscopy, we detect a gap of ~0.8 electron volt and conductive edge states consistent with theory. Our combined theoretical and experimental results demonstrate a concept for a quantum spin Hall wide-gap scenario, where the chemical potential resides in the global system gap, ensuring robust edge conductance.

中文翻译：

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SiC 衬底上的铋：高温量子自旋霍尔材料的候选材料

制作大间隙拓扑绝缘体 尽管对基础研究感兴趣，拓扑绝缘体 (TI) 尚未发挥其技术潜力。这部分是因为它们受保护的表面边缘状态通常存在于狭窄的能隙内，其奇异的传输特性被普通的大块材料所淹没。雷斯等人。表明明智地选择材料可以使间隙足够宽，从而使拓扑特性在室温下变得明显。数值计算表明，在 SiC(0001) 上生长的单层铋是具有大能隙的二维 TI。研究人员制造了这种异质结构，并使用扫描隧道光谱对其进行了表征。实验测量间隙的大小与计算一致。科学，这个问题 p。287 扫描隧道光谱表明大的能隙和导电边缘态，与计算一致。量子自旋霍尔材料有望成为具有无耗散自旋电流的革命性器件，但由于能隙较小，因此需要低温。在这里，我们从理论上表明，在利用原子自旋轨道耦合的范式中，可以实现具有大能隙的室温状态。该概念基于高原子序数元素的衬底支撑单层，并通过实验实现为绝缘碳化硅衬底 SiC(0001) 顶部的铋蜂窝晶格。使用扫描隧道光谱，我们检测到约 0.8 电子伏特的间隙和与理论一致的导电边缘状态。