Observation of Double-Dome Superconductivity in Potassium-Doped FeSe Thin Films
Observation of Double-Dome Superconductivity in Potassium-Doped FeSe Thin Films
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钾掺杂 FeSe 薄膜中双穹顶超导性的观察
DOI：
10.1103/physrevlett.116.157001
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发表时间：
2016-04-11
影响因子：
8.6
通讯作者：
Xue, Qi-Kun
中科院分区：
文献类型：
--
作者：
Song, Can-Li;Zhang, Hui-Min;Xue, Qi-Kun
本文报道了在石墨化SiC（0001）衬底上生长的碱金属钾（K-）掺杂FeSe超导薄膜中出现的两个不连续的超导圆顶。超导电性在较低的T-c圆顶中表现出对K剂量的超敏性，而在重电子掺杂的较高的T-c圆顶中，它变得空间均匀并且对无序具有鲁棒性，支持传统的库珀配对机制。此外，重K掺杂的多层FeSe膜都显示出类似于14 meV的大的超导能隙，与膜厚度无关，仅在最顶部的FeSe层中验证了较高的T-c超导性。双圆顶超导相的不寻常发现是对FeSe衍生超导体中超导性的机械理解的一步。
We report on the emergence of two disconnected superconducting domes in alkali-metal potassium-(K-) doped FeSe ultrathin films grown on graphitized SiC(0001). The superconductivity exhibits hypersensitivity to K dosage in the lower-T-c dome, whereas in the heavily electron-doped higher-T-c dome it becomes spatially homogeneous and robust against disorder, supportive of a conventional Cooper-pairing mechanism. Furthermore, the heavily K-doped multilayer FeSe films all reveal a large superconducting gap of similar to 14 meV, irrespective of film thickness, verifying the higher-T-c superconductivity only in the topmost FeSe layer. The unusual finding of a double-dome superconducting phase is a step towards the mechanistic understanding of superconductivity in FeSe-derived superconductors.