The iron-based superconductors are an ideal platform to reveal the enigma of the unconventional superconductivity and potential topological superconductivity. Among them, the monolayer Fe(Se,Te)/SrTiO₃(001), which is proposed to be topological nontrivial, shows interface-enhanced high-temperature superconductivity in the two-dimensional limit. However, the experimental studies on the superconducting pairing mechanism of monolayer Fe(Se,Te) films are still limited. Here, by measuring the quasiparticle interference in monolayer Fe(Se,Te)/SrTiO₃(001), we report the observation of the anisotropic structure of the large superconducting gap and the sign change of the superconducting gap on different electron pockets. The results are well consistent with the “bonding-antibonding” s_±-wave pairing symmetry driven by spin fluctuations in conjunction with spin-orbit coupling. Our work is of basic significance not only for a unified superconducting formalism in the iron-based superconductors, but also for understanding of topological superconductivity in high-temperature superconductors.

中文翻译：

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单层 Fe(Se,Te) 中的各向异性间隙结构和符号反转对称性

铁基超导体是揭示非常规超导性和潜在拓扑超导性之谜的理想平台。其中，被认为是拓扑非平凡的单层Fe(Se,Te)/SrTiO ₃ (001)在二维极限内表现出界面增强的高温超导性。然而，单层Fe(Se,Te)薄膜的超导配对机制的实验研究仍然有限。_{在这里，通过测量单层 Fe(Se,Te)/SrTiO 3} (001)中的准粒子干涉，我们报告了对大超导间隙各向异性结构的观察以及不同电子袋上超导间隙的符号变化。结果与“bonding-antibonding”非常吻合s _± - 由自旋波动和自旋轨道耦合驱动的波配对对称性。我们的工作不仅对统一铁基超导体的超导形式具有基础意义，而且对理解高温超导体的拓扑超导性也具有基础意义。