Comment on “Superconductivity in Kagome Metal YRu₃Si₂ with Strong Electron Correlations”

Recently, Gong et al. Chin. Phys. Lett. 39 087401 (2022) reported the results of a detailed study of the physical properties of high-quality YRu₃Si₂ single crystals with the Ru kagome lattice in the normal and superconducting states. One of the reported parameters, the ground-state penetration depth, λ_GL(0, l) = 24.8 nm, was deduced from the lower critical field, H_c1(T, l). From the deduced λ_GL(0, l), the authors calculated the ground-state values for the Ginzburg-Landau parameter κ_GL(0, l)=1.11 and the thermodynamic critical field B_c(0, l) = 0.42 T. Here I argue that the reported values of λ_GL(0, l), κ_GL(0, l), and B_c(0, l) are incorrect since the equation for the lower critical field H_c1(T, l), used by the authors to derive λ_GL(0, l), is invalid as it has two roots. Correct values deduced from the experimental data reported by Gong et al. are λ_GL(0, l) = 110.4 nm, κ_GL(0, l) = 4.92, and B_c(0, l) = 0.094 T, which differ by a factor of 4.5 from reported values.