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arXiv · 1511.02007

Observation of Double-Dome Superconductivity in Potassium-Doped FeSe Thin Films

Can-Li Song·Hui-Min Zhang·Yong Zhong·Xiao-Peng Hu·Shuai-Hua Ji·Lili Wang·Ke He·Xu-Cun Ma·Qi-Kun Xue
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Abstract

We report on the emergence of two disconnected superconducting domes in alkali-metal potassium (K)-doped FeSe ultra-thin films grown on graphitized SiC(0001). The superconductivity exhibits hypersensitivity to K dosage in the lower-Tc dome, whereas in the heavily electron-doped higher-Tc 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 ~ 14 meV, irrespective of film thickness, verifying the higher-Tc superconductivity only in the topmost FeSe layer. The unusual finding of a double-dome superconducting phase has stepped towards the mechanistic understanding of superconductivity in FeSe-derived superconductors.

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Can-Li Song, Hui-Min Zhang, Yong Zhong, Xiao-Peng Hu, Shuai-Hua Ji, Lili Wang, Ke He, Xu-Cun Ma, Qi-Kun Xue. 2016-04-13. Observation of Double-Dome Superconductivity in Potassium-Doped FeSe Thin Films. https://doi.org/10.1103/physrevlett.116.157001

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