Penetration depth, multiband superconductivity, and absence of muon-induced perturbation in superconductingPrOs4Sb12

Abstract

Transverse-field muon spin rotation $(\text{TF-}\ensuremath{\mu}\text{SR})$ experiments in the heavy-fermion superconductor ${\text{PrOs}}_{4}{\text{Sb}}_{12}({T}_{c}=1.85\text{ }\text{K})$ suggest that the superconducting penetration depth $\ensuremath{\lambda}(T)$ is temperature independent at low temperatures, consistent with a gapped quasiparticle excitation spectrum. In contrast, radio frequency inductive measurements yield a stronger temperature dependence of $\ensuremath{\lambda}(T)$, indicative of point nodes in the gap. Muon Knight-shift measurements in the normal state of ${\text{PrOs}}_{4}{\text{Sb}}_{12}$ suggest that the perturbing effect of the muon charge on the neighboring ${\text{Pr}}^{3+}$ crystalline electric field is negligibly small and therefore is unlikely to cause the difference between the $\text{TF-}\ensuremath{\mu}\text{SR}$ and rf results. The discrepancy appears to be related to multiband superconductivity in ${\text{PrOs}}_{4}{\text{Sb}}_{12}$.