Given the rarity of metallic systems that exhibit ferroelectric-like transitions, it is apparently challenging to find a system that simultaneously possesses superconductivity and ferroelectric-like structural instability. Here, we report the observation of superconductivity at 2.4 K in a layered semimetal SrAuBi characterized by strong spin–orbit coupling (SOC) and ferroelectric-like lattice distortion. Single crystals of SrAuBi have been successfully synthesized and found to show a polar-nonpolar structure transition at 214 K, which is associated with the buckling of Au-Bi honeycomb lattice. On the basis of the band calculations considering SOC, we found significant Rashba-type spin splitting and symmetry-protected multiple Dirac points near the Fermi level. We believe that this discovery opens up new possibilities of pursuing exotic superconducting states associated with the semimetallic band structure without space inversion symmetry and the topological surface state with the strong SOC.

鉴于表现出类铁电转变的金属系统的罕见性，找到一种同时具有超导性和类铁电结构不稳定性的系统显然具有挑战性。在这里，我们报告了在层状半金属 SrAuBi 中观察到的 2.4 K 超导性，其特征是强自旋轨道耦合 (SOC) 和类铁电晶格畸变。 SrAuBi 单晶已成功合成，并发现在 214°K 时表现出极性-非极性结构转变，这与 Au-Bi 蜂窝晶格的屈曲有关。在考虑 SOC 的能带计算的基础上，我们发现费米能级附近存在显着的 Rashba 型自旋分裂和对称保护的多个狄拉克点。我们相信这一发现为追求与无空间反演对称性的半金属能带结构相关的奇异超导态和具有强SOC的拓扑表面态开辟了新的可能性。