Emergent charge order in pressurized kagome superconductor CsV 3 Sb 5 .

The discovery of several electronic orders in kagome superconductors AV 3 Sb 5 (A means K, Rb, Cs) provides a promising platform for exploring unprecedented emergent physics 1-9 . Under moderate pressure (<2.2 GPa), the triple-Q charge density wave (CDW) order is monotonically suppressed by pressure, while the superconductivity shows a two-dome-like behaviour, suggesting an unusual interplay between superconductivity and CDW order 10,11 . Given that time-reversal symmetry breaking and electronic nematicity have been revealed inside the triple-Q CDW phase 8,9,12,13 , understanding this CDW order and its interplay with superconductivity becomes one of the core questions in AV 3 Sb 5 (refs. 3,5,6 ). Here, we report the evolution of CDW and superconductivity with pressure in CsV 3 Sb 5 by 51 V nuclear magnetic resonance measurements. An emergent CDW phase, ascribed to a possible stripe-like CDW order with a unidirectional 4a 0 modulation, is observed between P c1  ≅ 0.58 GPa and P c2  ≅ 2.0 GPa, which explains the two-dome-like superconducting behaviour under pressure. Furthermore, the nuclear spin-lattice relaxation measurement reveals evidence for pressure-independent charge fluctuations above the CDW transition temperature and unconventional superconducting pairing above P c2 . Our results not only shed new light on the interplay of superconductivity and CDW, but also reveal new electronic correlation effects in kagome superconductors AV 3 Sb 5 .