Realization of topological superconductors (TSCs) hosting Majorana fermions is an exciting challenge in materials science. Majorana fermions are predicted to emerge at vortex cores of two-dimensional (2D) TSCs and at both ends of one-dimensional (1D) TSCs; these two types of TSCs have been explored independently in different materials. Here, a system which has a potential to access both 1D and 2D TSCs in a single platform, Pb(111)/Bi(111) heterostructure, is proposed. One to twenty bilayers (BLs) of Bi(111) ultra-thin films are epitaxially fabricated on TlBiSe$_2$, and an intriguing evolution of electronic states upon variation of Bi-layer thickness is revealed by angle-resolved photoemission spectroscopy. The metallic quantum-well states at 1–2BLs are found to turn into the Rashba states at 5–20BLs, via the semiconducting states at 3BL. Fabrication of a Pb(111) film on 20BL Bi(111) enables observation of the proximity-induced superconductivity in Bi(111) as evident from a 1 meV energy gap at 5 K; these energy and temperature scales are considerably larger than those of Rashba superconductors. The Pb/Bi heterostructure serves as a versatile platform to study the interplay among proximity-induced superconductivity, band structure, and topology.

中文翻译：

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Pb/Bi异质结构作为实现拓扑超导的通用平台

实现承载马约拉纳费米子的拓扑超导体 (TSC) 是材料科学中令人兴奋的挑战。预计马约拉纳费米子将出现在二维 (2D) TSC 的涡核和一维 (1D) TSC 的两端；这两种类型的 TSC 已在不同材料中独立探索。在这里，提出了一种有可能在单个平台上访问一维和二维 TSC 的系统，即 Pb(111)/Bi(111) 异质结构。在 TlBiSe$_2$ 上外延制造了 1 到 20 个 Bi(111) 超薄膜双层 (BL)，角分辨光电子能谱揭示了随着 Bi(111) 层厚度变化的电子态的有趣演变。发现 1-2BLs 的金属量子阱态通过 3BLs 的半导体态转变为 5-20BLs 的 Rashba 态。在 20BL Bi(111) 上制造 Pb(111) 薄膜可以观察 Bi(111) 中的邻近感应超导性，这从 5 K 时的 1 meV 能隙可以看出；这些能量和温度尺度比 Rashba 超导体大得多。Pb/Bi 异质结构用作研究邻近诱导超导、能带结构和拓扑结构之间相互作用的通用平台。