Wei Zhongxu, Qin Shengshan, Ding Cui, Wu Xianxin, Hu Jiangping, Sun Yu-Jie, Wang Lili, Xue Qi-Kun
Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China.
State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China.
Nat Commun. 2023 Aug 31;14(1):5302. doi: 10.1038/s41467-023-40931-5.
Determining the pairing symmetry of single-layer FeSe on SrTiO is the key to understanding the enhanced pairing mechanism. It also guides the search for superconductors with high transition temperatures. Despite considerable efforts, it remains controversial whether the symmetry is the sign-preserving s- or the sign-changing s-wave. Here, we investigate the pairing symmetry of single-layer FeSe from a topological point of view. Using low-temperature scanning tunneling microscopy/spectroscopy, we systematically characterize the superconducting states at edges and corners of single-layer FeSe. The tunneling spectra collected at edges and corners show a full energy gap and a substantial dip, respectively, suggesting the absence of topologically non-trivial edge and corner modes. According to our theoretical calculations, these spectroscopic features can be considered as strong evidence for the sign-preserving s-wave pairing in single-layer FeSe.
确定单层FeSe在SrTiO上的配对对称性是理解增强配对机制的关键。它还指导着对具有高转变温度的超导体的探索。尽管付出了巨大努力，但关于其对称性是保号s波还是变号s波仍存在争议。在此，我们从拓扑学角度研究单层FeSe的配对对称性。利用低温扫描隧道显微镜/光谱学，我们系统地表征了单层FeSe边缘和角落处的超导态。在边缘和角落处收集的隧道谱分别显示出一个完整的能隙和一个明显的凹陷，这表明不存在拓扑非平凡的边缘和角落模式。根据我们的理论计算，这些光谱特征可被视为单层FeSe中保号s波配对的有力证据。
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