Interest in superconducting proximity effect has been revived by the exploitation of Andreev states and by the possible emergence of Majorana bound states at the interface. Spectroscopy of these states has been so far restricted to just a handful of superconductor-metal systems in the diffusion regime, whereas reports in otherwise clean superconductor-superconductor heterojunctions are scarce. Here, we realize molecular beam epitaxy growth of atomically sharp planar heterojunctions between Pb and a topological superconductor candidate RhPb₂ that allows us to spectroscopically image the proximity effect in the clean limit. The measured energy spectra of RhPb₂ vary with the spatial separation from proximal Pb, and exhibit unusual modifications in the pairing gap structure and size that extend over a distance far beyond the coherence length. This anomalously long-range proximity (LRP) effect breaks the rotational symmetry of Cooper pair potential in real space and largely deforms the Abrikosov vortex cores. Our work opens promising avenues for fundamental studies of the Andreev physics and extraordinary states in clean superconducting heterojunctions.

对 Andreev 态的开发以及界面处可能出现的马约拉纳束缚态重新唤起了人们对超导邻近效应的兴趣。到目前为止，这些状态的光谱学仅限于扩散区域中的少数超导体-金属系统，而在其他方面清洁的超导体-超导体异质结方面的报道很少。在这里，我们实现了 Pb 和拓扑超导体候选 RhPb ₂之间原子级尖锐平面异质结的分子束外延生长，这使我们能够在清洁极限内对邻近效应进行光谱成像。_{RhPb 2}的实测能谱随着与近端 Pb 的空间分离而变化，并且在配对间隙结构和尺寸上表现出不寻常的修改，其延伸距离远远超过相干长度。这种异常的远程邻近 (LRP) 效应打破了真实空间中库珀对势的旋转对称性，并在很大程度上使 Abrikosov 涡核发生变形。我们的工作为 Andreev 物理学和清洁超导异质结中的非凡状态的基础研究开辟了有前途的途径。