Highly Robust Reentrant Superconductivity in CsV3Sb5 under Pressure

We present the superconducting (SC) property and high-robustness of structural stability of kagome CsV3Sb5 under in situ high pressures. For the initial SC-I phase, its T (c) is quickly enhanced from 3.5 K to 7.6 K and then totally suppressed at P similar to 10 GPa. With further increasing pressure, an SC-II phase emerges at P similar to 15 GPa and persists up to 100 GPa. The T (c) rapidly increases to the maximal value of 5.2 K at P = 53.6 GPa and slowly decreases to 4.7 K at P = 100 GPa. A two-dome-like variation of T (c) in CsV3Sb5 is concluded here. The Raman measurements demonstrate that weakening of E (2g) mode and strengthening of E (1g) mode occur without phase transition in the SC-II phase, which is supported by the results of phonon spectra calculations. Electronic structure calculations reveal that exertion of pressure may bridge the gap of topological surface nontrivial states near E (F), i.e., disappearance of Z (2) invariant. Meanwhile, the Fermi surface enlarges significantly, consistent with the increased carrier density. The findings here suggest that the change of electronic structure and strengthened electron-phonon coupling should be responsible for the pressure-induced reentrant SC.