Double Superconducting Dome and Triple Enhancement of Tc in the Kagome Superconductor CsV3Sb5 under High Pressure

CsV3Sb5 is a newly discovered Z(2) topological kagome metal showing the coexistence of a charge-density-wave (CDW)-like order at T* = 94 K and superconductivity (SC) at T-c = 2.5 K at ambient pressure. Here, we study the interplay between CDW and SC in CsV3Sb5 via measurements of resistivity, dc and ac magnetic susceptibility under various pressures up to 6.6 GPa. We find that the CDW transition decreases with pressure and experience a subtle modification at P-c1 approximate to 0.6-0.9 GPa before it vanishes completely at P-ct2 approximate to GPa. Correspondingly, T-c(P) displays an unusual M-shaped double dome with two maxima around P-c1 and P(c2 )respectively, leading to a tripled enhancement of T-c to about 8 K at 2 GPa. The obtained temperature-pressure phase diagram resembles those of unconventional superconductors, illustrating an intimated competition between CDW-like order and SC. The competition is found to be particularly strong for the intermediate pressure range P-c1 <= P <= P-c2 as evidenced by the broad superconducting transition and reduced superconducting volume fraction. The modification of CDW order around P-c1 has been discussed based on the band structure calculations. This work not only demonstrates the potential to raise T-c of the V-based kagome superconductors, but also offers more insights into the rich physics related to the electron correlations in this novel family of topological kagomc metals.

Automated summary

The study reveals that the CDW transition in CsV3Sb5 decreases with pressure, with an unusual M-shaped double dome in the T-c(P) curve showing enhancement up to 8 K at 2 GPa. This indicates a strong competition between CDW-like order and SC, particularly in the intermediate pressure range of P-c1 <= P <= P-c2.