Strain-Tuned Nodal Superconductivity in the Charge-Ordered Kagome Metal CsV3⁢Sb5

The nature of the superconducting pairing symmetry in the kagome metal CsV3⁢Sb5 and its relationship with the charge density wave (CDW) order are central unresolved issues. Here, we investigate the evolution of superconductivity in CsV3⁢Sb5 under in situ uniaxial pressure using 121Sb nuclear quadrupole resonance (NQR). We find that tensile strain significantly enhances the superconducting transition temperature, 𝑇c, while the CDW remains unchanged, demonstrating that superconductivity can be tuned independently of the bulk charge order. At a tensile strain of 𝜖 =+0.90%, the nuclear spin-lattice relaxation rate reveals a remarkable double transition: an upper transition at 𝑇c⁢1=3.6  K to a nodal gap state, and a lower one at 𝑇c⁢2=3.0  K characterized by a nodeless gap. These results evidence degenerate superconducting states with different gap symmetry in the kagome metal at ambient pressure which split under strain. Our Letter demonstrates a high tunability of superconductivity by uniaxial pressure.

This is an Accepted Manuscript of an article published by American Physical Society (APS).