Conventional superconductivity in the doped kagome superconductor Cs(V0.86Ta0.14)3Sb5 from vortex lattice studies

• Published in: Nature communications Vol. 15; no. 1; pp. 6467 - 7
• Main Authors: Xie, Yaofeng, Chalus, Nathan, Wang, Zhiwei, Yao, Weiliang, Liu, Jinjin, Yao, Yugui, White, Jonathan S., DeBeer-Schmitt, Lisa M., Yin, Jia-Xin, Dai, Pengcheng, Eskildsen, Morten Ring
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 31.07.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/1003; 639/766/119/995; Bulk density; Charge density waves; Coexistence; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Electron spin; Electronic properties and materials; Heavy metals; Humanities and Social Sciences; multidisciplinary; Neutron scattering; Phase diagrams; Science; Science (multidisciplinary); Superconducting properties and materials; Superconductivity; Temperature dependence; Unconventional superconductors; Vortices
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-50856-2

A hallmark of unconventional superconductors is a complex electronic phase diagram where intertwined orders of charge-spin-lattice degrees of freedom compete and coexist. While the kagome metals such as CsV 3 Sb 5 also exhibit complex behavior, involving coexisting charge density wave order and superconductivity, much is unclear about the microscopic origin of the superconducting pairing. We study the vortex lattice in the superconducting state of Cs(V 0.86 Ta 0.14 ) 3 Sb 5 , where the Ta-doping suppresses charge order and enhances superconductivity. Using small-angle neutron scattering, a strictly bulk probe, we show that the vortex lattice exhibits a strikingly conventional behavior. This includes a triangular symmetry with a period consistent with 2 e -pairing, a field dependent scattering intensity that follows a London model, and a temperature dependence consistent with a uniform superconducting gap. Our results suggest that optimal bulk superconductivity in Cs(V 1− x Ta x ) 3 Sb 5 arises from a conventional Bardeen-Cooper-Schrieffer electron-lattice coupling, different from spin fluctuation mediated unconventional copper- and iron-based superconductors. The mechanism of superconductivity in layered kagome metals remains unclear, however its coexistence with charge order suggests exotic interpretations. Here the authors study the vortex lattice in the superconducting state of Ta-doped CsV 3 Sb 5 with suppressed charge order, suggesting conventional pairing.