A topological insulator (TI) interfaced with an s-wave superconductor has been predicted to host topological superconductivity. Although the growth of epitaxial TI films on s-wave superconductors has been achieved by molecular-beam epitaxy, it remains an outstanding challenge for synthesizing atomically thin TI/superconductor heterostructures, which are critical for engineering the topological superconducting phase. Here we used molecular-beam epitaxy to grow Bi₂Se₃ films with a controlled thickness on monolayer NbSe₂ and performed in situ angle-resolved photoemission spectroscopy and ex situ magnetotransport measurements on these heterostructures. We found that the emergence of Rashba-type bulk quantum-well bands and spin-non-degenerate surface states coincides with a marked suppression of the in-plane upper critical magnetic field of the superconductivity in Bi₂Se₃/monolayer NbSe₂ heterostructures. This is a signature of a crossover from Ising- to Rashba-type superconducting pairings, induced by altering the Bi₂Se₃ film thickness. Our work opens a route for exploring a robust topological superconducting phase in TI/Ising superconductor heterostructures.

已预测与s波超导体连接的拓扑绝缘体 (TI)具有拓扑超导性。尽管s波超导体上外延 TI 薄膜的生长已通过分子束外延实现，但合成原子级薄 TI/超导体异质结构仍然是一个突出的挑战，这对于设计拓扑超导相至关重要。在这里，我们使用分子束外延在单层 NbSe ₂上生长厚度可控的Bi ₂ Se _3薄膜并对这些异质结构进行了原位角分辨光电子能谱和非原位磁传输测量。我们发现 Rashba 型体量子阱带和自旋非简并表面态的出现与 Bi ₂ Se ₃ /单层 NbSe ₂异质结构中超导性的面内上临界磁场的显着抑制一致。这是从 Ising 型到 Rashba 型超导对的交叉的标志，通过改变 Bi ₂ Se ₃膜厚度诱导。我们的工作为探索 TI/伊辛超导体异质结构中稳健的拓扑超导相开辟了道路。