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Superconductivity under pressure in a chromium-based kagome metal

  • Yi Liu,
  • Zi-Yi Liu,
  • Jin-Ke Bao,
  • Peng-Tao Yang,
  • Liang-Wen Ji,
  • Si-Qi Wu,
  • Qin-Xin Shen,
  • Jun Luo,
  • Jie Yang,
  • Ji-Yong Liu,
  • Chen-Chao Xu,
  • Wu-Zhang Yang,
  • Wan-Li Chai,
  • Jia-Yi Lu,
  • Chang-Chao Liu,
  • Bo-Sen Wang,
  • Hao Jiang,
  • Qian Tao,
  • Zhi Ren,
  • Xiao-Feng Xu,
  • Chao Cao,
  • Zhu-An Xu,
  • Rui Zhou,
  • Jin-Guang Cheng,
  • Guang-Han Cao

摘要

Superconductivity in a highly correlated kagome system has been theoretically proposed for years (refs. 15), yet the experimental realization is hard to achieve6,7. The recently discovered vanadium-based kagome materials8, which exhibit both superconductivity911 and charge-density-wave orders1214, are nonmagnetic8,9 and weakly correlated15,16. Thus these materials are unlikely to host the exotic superconductivity theoretically proposed. Here we report the discovery of a chromium-based kagome metal, CsCr3Sb5, which is contrastingly featured with strong electron correlations, frustrated magnetism and characteristic flat bands close to the Fermi level. Under ambient pressure, this kagome metal undergoes a concurrent structural and magnetic phase transition at 55 K, with a stripe-like 4a0 structural modulation. At high pressure, the phase transition evolves into two transitions, possibly associated with charge-density-wave and antiferromagnetic spin-density-wave orderings. These density-wave-like orders are gradually suppressed with pressure and, remarkably, a superconducting dome emerges at 3.65–8.0 GPa. The maximum of the superconducting transition temperature, Tcmax = 6.4 K, appears when the density-wave-like orders are completely suppressed at 4.2 GPa, and the normal state exhibits a non-Fermi-liquid behaviour, reminiscent of unconventional superconductivity and quantum criticality in iron-based superconductors17,18. Our work offers an unprecedented platform for investigating superconductivity in correlated kagome systems.