Fig. 4: Summary of muon-spin rotation (μSR) experiments in the superconducting state of Cs(V_0.93Nb_0.07)₃Sb₅.

a Transverse-field (TF) μSR spectra collected above (10 K, purple) and below (1.5 K, red) T_C after field-cooling the sample from above T_C in an applied field of 10mT. The error bars are the standard error of the mean (s.e.m.) in about 10⁶ events. b Fourier transforms of the data from (a). c Temperature dependence of the superconducting muon spin depolarisation rate, σ_sc and inverse squared penetration depth, λ⁻² measured in 10 mT. The red and green solid lines show the fit of a nodeless s-wave gap and dirty-d wave model, respectively. The inset shows λ⁻² against the low-temperature data on a log–log scale. The error bars represent the standard deviation of the fit parameters. d Response of the internal magnetic field, μ₀H_int, in the superconducting state has the expected diamagnetic shift.