Emergent charge order in pressurized kagome superconductor CsV3Sb5

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 V-51 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 congruent to 0.58 GPa and P-c2 congruent to 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).

Automated summary

The discovery of electronic orders in kagome superconductors AV(3)Sb(5) opens up a promising avenue for exploring new emergent physics. Pressure experiments on CsV(3)Sb(5) reveal a new CDW phase between P-c1 ≈ 0.58 GPa and P-c2 ≈ 2.0 GPa, attributed to a possible stripe-like CDW order, explaining the two-dome-like superconducting behavior under pressure. Additionally, nuclear spin-lattice relaxation measurements show evidence for pressure-independent charge fluctuations above the CDW transition temperature and unconventional superconducting pairing above P-c2.