Xu Yu, Rong Hongtao, Wang Qingyan, Wu Dingsong, Hu Yong, Cai Yongqing, Gao Qiang, Yan Hongtao, Li Cong, Yin Chaohui, Chen Hao, Huang Jianwei, Zhu Zhihai, Huang Yuan, Liu Guodong, Xu Zuyan, Zhao Lin, Zhou X J
National Lab for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
University of Chinese Academy of Sciences, Beijing, China.
Nat Commun. 2021 May 14;12(1):2840. doi: 10.1038/s41467-021-23106-y.
Single-layer FeSe films grown on the SrTiO substrate (FeSe/STO) have attracted much attention because of their possible record-high superconducting critical temperature (T) and distinct electronic structures. However, it has been under debate on how high its T can really reach due to the inconsistency of the results from different measurements. Here we report spectroscopic evidence of superconductivity pairing at 83 K in single-layer FeSe/STO films. By preparing high-quality single-layer FeSe/STO films, we observe strong superconductivity-induced Bogoliubov back-bending bands that extend to rather high binding energy ~ 100 meV by high-resolution angle-resolved photoemission measurements. They provide a new definitive benchmark of superconductivity pairing that is directly observed up to 83 K. Moreover, we find that the pairing state can be further divided into two temperature regions. These results indicate that either T as high as 83 K is achievable, or there is a pseudogap formation from superconductivity fluctuation in single-layer FeSe/STO films.
生长在钛酸锶衬底（FeSe/STO）上的单层FeSe薄膜因其可能创纪录的高超导临界温度（Tc）和独特的电子结构而备受关注。然而，由于不同测量结果的不一致，其Tc究竟能达到多高一直存在争议。在此，我们报告了单层FeSe/STO薄膜在83 K时超导配对的光谱证据。通过制备高质量的单层FeSe/STO薄膜，我们通过高分辨率角分辨光电子能谱测量观察到强超导诱导的博戈留波夫反弯能带，其延伸到相当高的结合能~100毫电子伏特。它们提供了一个新的超导配对的明确基准，该基准在高达83 K时被直接观测到。此外，我们发现配对态可进一步分为两个温度区域。这些结果表明，单层FeSe/STO薄膜要么可以实现高达83 K的Tc，要么存在由超导涨落形成的赝能隙。
