Coexistence of Dirac Nodal Lines and Rashba Bands in the Topological Superconductor Candidate AuSn<sub>4</sub>.

Deng, Liwei; Huang, Yu; Li, Tongrui; Liu, Xiangqi; Chen, Shilong; Ma, Xun; Wang, Jiameng; Liu, Zhengtai et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

The interplay between spin-orbit coupling and superconductivity in topologically nontrivial materials provides a fertile setting for realizing unconventional pairing states and Majorana bound modes. AuSn<sub>4</sub>, a noble metal stannide isostructural to PtSn<sub>4</sub> and PdSn<sub>4</sub>, has recently been identified as a candidate two-dimensional superconductor exhibiting vortex core zero modes consistent with mixed s + p pairing symmetry. Here, we present a comprehensive study using angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES (SARPES), unveiling the coexistence of Rashba-split surface bands and Dirac nodal lines in AuSn<sub>4</sub>. We further identify a surface-confined van Hove singularity (VHS) in close proximity to the Dirac point near the Brillouin zone boundary. Together, these results position AuSn<sub>4</sub> as a compelling superconducting platform within which Rashba type surface states and nontrivial topological bands reside, offering microscopic insight into the emergence of unconventional pairing and the prospects for topological superconductivity.