标题： 螺旋边缘态和在FeTe$_{0.55}$Se$_{0.45}$上的Bi岛增强的超导能隙 显示英文标题

标题： Helical edge states and enhanced superconducting gaps in Bi islands on FeTe$_{0.55}$Se$_{0.45}$

摘要： 通过在沉积在FeTe$_{0.55}$Se$_{0.45}$超导体上的某些大Bi岛上测量扫描隧道谱，我们观察到在靠近岛边缘的谱中约在$\pm 1.0$ meV处有双峰的拓扑间隙内边缘态的清晰证据。 边缘态在宽度为2-3 nm的岛内部延伸。 正负能量处的两个边缘态峰随着磁场的增加而向更高的值移动，并在FeTe$_{0.55}$Se$_{0.45}$的转变温度$T_\mathrm{c}$附近消失。 这些边缘态被解释为由Bi岛的强自旋轨道耦合效应引起的反向传播的拓扑边缘态，当边缘态在一些小的Bi岛中相互接触时，零能模出现。 同时，在这些Bi岛的中心区域观察到了增强的超导能隙，这可能是由拓扑表面态的增强配对势引起的。 我们的观察结果为在特定Bi岛生长于FeTe$_{0.55}$Se$_{0.45}$基底上的非平凡拓扑超导性提供了有用的信息。 显示英文摘要

摘要： By measuring scanning tunneling spectroscopy on some large Bi islands deposited on FeTe$_{0.55}$Se$_{0.45}$ superconductors, we observe clear evidence of topological in-gap edge states with double peaks at about $\pm 1.0$ meV on the spectra measured near the perimeter of the islands. The edge states spread towards the inner side of the islands over a width of 2-3 nm. The two edge-state peaks at positive and negative energies both move to higher values with increase of the magnetic field, and they disappear near the transition temperature $T_\mathrm{c}$ of FeTe$_{0.55}$Se$_{0.45}$. The edge states are interpreted as the counter-propagating topological edge states induced by the strong spin-orbit coupling effect of the Bi island, and the zero-energy mode emerges when the edge states touch each other in some small Bi islands. Meanwhile, enhanced superconducting gaps are observed in the central regions of these Bi islands, which may be induced by the enhanced pair potential of the topological surface state. Our observations provide useful message for the nontrivial topological superconductivity on specific Bi islands grown on FeTe$_{0.55}$Se$_{0.45}$ substrate.