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arXiv · 2112.12902

Protonation-induced discrete superconducting phases in bulk FeSe single crystals

Yan Meng·Xiangzhuo Xing·Xiaolei Yi·Bin Li·Nan Zhou·Meng Li·Yufeng Zhang·Wei Wei·Jiajia Feng·Kensei Terashima·Yoshihiko Takano·Yue Sun·Zhixiang Shi
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Abstract

The superconducting transition temperature, $T_{\rm{c}}$, of FeSe can be significantly enhanced several-fold by applying pressure, electron doping, intercalating spacing layer, and reducing dimensionality. Various ordered electronic phases, such as nematicity and spin density waves, have also been observed accompanying high-$T_{\rm{c}}$ superconductivity. Investigation on the evolution of the electronic structure with $T_{\rm{c}}$ is essential to understanding electronic behavior and high-$T_{\rm{c}}$ superconductivity in FeSe and its derived superconductors. In this report, we have found a series of discrete superconducting phases, with a maximum $T_{\rm{c}}$ up to 44 K, in H$^+$-intercalated FeSe single crystals using an ionic liquid gating method. Accompanied with the increase of $T_{\rm{c}}$, suppression of the nematic phase and evolution from non-Fermi-liquid to Fermi-liquid behavior was observed. An abrupt change in the Fermi surface topology was proposed to explain the discrete superconducting phases. A band structure that favors the high-$T_{\rm{c}}$ superconducting phase was also revealed.

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Yan Meng, Xiangzhuo Xing, Xiaolei Yi, Bin Li, Nan Zhou, Meng Li, Yufeng Zhang, Wei Wei, Jiajia Feng, Kensei Terashima, Yoshihiko Takano, Yue Sun, Zhixiang Shi. 2021-12-24. Protonation-induced discrete superconducting phases in bulk FeSe single crystals. https://doi.org/10.1103/physrevb.105.134506

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