The transition metal kagome lattice materials host frustrated, correlated and topological quantum states of matter^{1,2,3,4,5,6,7,8,9}. Recently, a new family of vanadium-based kagome metals, AV₃Sb₅ (A = K, Rb or Cs), with topological band structures has been discovered^10,11. These layered compounds are nonmagnetic and undergo charge density wave transitions before developing superconductivity at low temperatures^{11,12,13,14,15,16,17,18,19}. Here we report the observation of unconventional superconductivity and a pair density wave (PDW) in CsV₃Sb₅ using scanning tunnelling microscope/spectroscopy and Josephson scanning tunnelling spectroscopy. We find that CsV₃Sb₅ exhibits a V-shaped pairing gap Δ ~ 0.5 meV and is a strong-coupling superconductor (2Δ/k_BT_c ~ 5) that coexists with 4a₀ unidirectional and 2a₀ × 2a₀ charge order. Remarkably, we discover a 3Q PDW accompanied by bidirectional 4a₀/3 spatial modulations of the superconducting gap, coherence peak and gap depth in the tunnelling conductance. We term this novel quantum state a roton PDW associated with an underlying vortex–antivortex lattice that can account for the observed conductance modulations. Probing the electronic states in the vortex halo in an applied magnetic field, in strong field that suppresses superconductivity and in zero field above T_c, reveals that the PDW is a primary state responsible for an emergent pseudogap and intertwined electronic order. Our findings show striking analogies and distinctions to the phenomenology of high-T_c cuprate superconductors, and provide groundwork for understanding the microscopic origin of correlated electronic states and superconductivity in vanadium-based kagome metals.

过渡金属 kagome 晶格材料主机受挫、相关和拓扑量子态的物质^{1,2,3,4,5,6,7,8,9}。最近，发现了具有拓扑能带结构的新钒基戈薇金属 AV ₃ Sb ₅（A = K、Rb 或 Cs）家族^10,11。这些层状化合物是非磁性的，在低温^{11,12,13,14,15,16,17,18,19}发展超导性之前会经历电荷密度波跃迁。在这里，我们报告了使用扫描隧道显微镜/光谱学和约瑟夫森扫描隧道光谱学对 CsV ₃ Sb _{5中非常规超导性和一对密度波 (PDW) 的观察。}我们发现 CsV₃ Sb ₅具有V型配对间隙Δ ~0.5 meV，是一种同时存在4 a ₀单向和2 a ₀  × 2 a ₀电荷序 的强耦合超导体(2 Δ / k _B T _c  ~ 5) 。值得注意的是，我们发现了一个 3Q PDW 伴随着双向 4 a ₀/3 隧道电导中超导间隙、相干峰和间隙深度的空间调制。我们将这种新颖的量子态称为与底层涡旋-反涡旋晶格相关的旋子 PDW，该晶格可以解释观察到的电导调制。在外加磁场、抑制超导性的强场和高于Tc的零场中探测涡晕中的电子态，表明 PDW 是导致出现赝能隙和交织电子序的主要状态_。我们的发现显示了与高温现象学的显着类比_和区别铜酸盐超导体，并为理解钒基可果美金属中相关电子态和超导性的微观起源提供基础。