Discrete Superconducting Phases in FeSe-derived Superconductors

ORAL

Abstract

A general feature of unconventional superconductors is the existence of a superconducting dome in the phase diagram, i.e., the continuous evolution of the transition temperature Tc with tuning parameters such as doping and pressure. For the simplest iron-based superconductor FeSe (Tc > 8 K), its Tc can be greatly enhanced by doping electrons via many ways, even up to 65 K in monolayer FeSe/SrTiO3 with the help of phonons. However, it remains controversial whether there exists a superconducting dome in these electron-doped FeSe-derived superconductors. Here, we report the observation of a series of discrete superconducting phases in FeSe thin flakes by finely tuning the intercalation of Li and Na ions with a solid ion gating technique. Such discrete superconducting phases contrast sharply to the superconducting dome in most unconventional superconductors. Our results demonstrate that the existence of discrete superconducting phases is intrinsic and universal in FeSe intercalated by alkali/alkaline earth/rear earth metals. It likely comes from the spontaneous phase separation of these ions between FeSe layers.

–

Presenters

  • Tianping Ying

    • Fudan University
    • Physics, Fudan University

Authors

  • Tianping Ying

    • Fudan University
    • Physics, Fudan University

  • Minxiang Wang

    • Fudan University

  • Ziyi Zhao

    • Fudan University

  • ZhiZhen Zhang

    • Institute of Physics, Chinese Academy of Sciences

  • Xiaoyu Jia

    • Fudan University

  • Yingcheng Li

    • Fudan University

  • Bin Lei

    • University of Science and Technology of China

  • Qing Li

    • Fudan University

  • Yunjie Yu

    • Fudan Univ
    • State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University
    • Fudan University

  • Erjian Cheng

    • Fudan University

  • zhenghua An

    • Fudan University

  • Yuanbo Zhang

    • Fudan Univ.
    • Fudan Univ
    • Fudan University

  • Wei Yang

    • Graduate School at Shenzhen, Tsinghua University

  • Xianhui Chen

    • University of Science and Technology of China
    • Department of Physics, University of Science and Technology of China
    • Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China

  • Shiyan Li

    • University of Sherbrooke
    • Fudan Univ
    • State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University
    • State Key Laboratory of Surface Physics and Laboratory of Advanced Materials, Department of Physics, Fudan University
    • Fudan University