Local spectroscopic evidence for a nodeless magnetic kagome superconductor CeRu 2 .

We report muon spin rotation ( µ SR) experiments on the microscopic properties of superconductivity and magnetism in the kagome superconductor CeRu 2 withTc≃5 K. From the measurements of the temperature-dependent magnetic penetration depth λ , the superconducting order parameter exhibits nodeless pairing, which fits best to an anisotropic s -wave gap symmetry. We further show that theTc/ λ -2 ratio is comparable to that of unconventional superconductors. Furthermore, the powerful combination of zero-field (ZF)- µ SR and high-field µ SR has been used to uncover magnetic responses across three characteristic temperatures, identified asT1∗≃110 K,T2∗≃65 K, andT3∗≃40 K. Our experiments classify CeRu 2 as an exceedingly rare nodeless magnetic kagome superconductor.