Ye Yuhan, Song Rui, Xiao Hongqin, Xian Guoyu, Guo Hui, Yang Haitao, Chen Hui, Gao Hong-Jun
Beijing National Center for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, PR China.
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, PR China.
Nano Lett. 2024 Oct 23;24(42):13455-13463. doi: 10.1021/acs.nanolett.4c04734. Epub 2024 Oct 11.
The noble metal alloy AuSn has recently been identified as an intrinsic surface topological superconductor, promisingly hosting the Majorana zero mode (MZM) for topological quantum computing. However, the atomic visualization of its nontrivial surface states and MZM remains elusive. Here, we report the direct observation of unconventional surface states and vortex zero mode in AuSn by scanning tunneling microscopy/spectroscopy. Unlike the trivial metallic bulk states of Sn-terminated surfaces, the Au-terminated surfaces exhibit pronounced surface states near the Fermi level, arising from unconventional Rashba bands characterized by shared helical spin textures. In the superconducting state, the Sn-terminated surfaces exhibit conventional Caroli-de Gennes-Matricon bound states, while the Au-terminated surfaces display sharp zero-energy core states resembling MZMs in a nonquantum-limit condition. This distinction may result from the dominant contribution of unconventional Rashba bands on the Au-terminated surface. Our results provide a new platform for studying termination-dependent topological surface states and MZM in noble-metal-based superconductors.
贵金属合金AuSn最近被确定为一种本征表面拓扑超导体，有望承载用于拓扑量子计算的马约拉纳零模（MZM）。然而，其非平凡表面态和MZM的原子可视化仍然难以实现。在此，我们通过扫描隧道显微镜/能谱报告了在AuSn中对非常规表面态和涡旋零模的直接观测。与Sn端表面的平凡金属体态不同，Au端表面在费米能级附近表现出明显的表面态，这源于具有共享螺旋自旋纹理的非常规 Rashba 能带。在超导态下，Sn端表面表现出传统的卡罗利 - 德热纳 - 马蒂康束缚态，而Au端表面则显示出在非量子极限条件下类似于MZM的尖锐零能芯态。这种差异可能源于非常规Rashba能带对Au端表面的主导贡献。我们的结果为研究基于贵金属的超导体中依赖于端接的拓扑表面态和MZM提供了一个新平台。
