Local spectroscopic evidence for a nodeless magnetic kagome superconductor CeRu${}_2$

Abstract

We report muon spin rotation ($\hat{I}¼$SR) experiments on the microscopic properties of superconductivity and magnetism in the kagome superconductor CeRu${}_2$ with $T_{\mathrm{c}}$~$\simeq$~5~K. From the measurements of the temperature-dependent magnetic penetration depth $\hat{I}»$, the superconducting order parameter exhibits nodeless pairing, which fits best to an anisotropic $s$-wave gap symmetry. We further show that the $T_{\mathrm{c}}$/$\hat{I}{»}^{-2}$ ratio is comparable to that of unconventional superconductors. Furthermore, the powerful combination of zero-field (ZF)-$\hat{I}¼$SR and high-field $\hat{I}¼$SR has been used to uncover magnetic responses across three characteristic temperatures, identified as $T_1^{\ast }$~$\simeq$~110~K, $T_2^{\ast }$~$\simeq$~65~K, and $T_3^{\ast }$~$\simeq$~40~K. Our experiments classify CeRu${}_2$ as an exceedingly rare nodeless magnetic kagome superconductor.

8 pages, 4 figures. arXiv admin note: text overlap with arXiv:2012.15654