muSR linewidth and isotropic pairing in superconducting PrOs4Sb12

TL;DR

This study uses muon spin rotation to reveal an isotropic superconducting gap in PrOs4Sb12, suggesting a unique pairing mechanism among heavy-fermion superconductors, with a notably short penetration depth.

Contribution

It provides the first evidence of isotropic pairing symmetry in PrOs4Sb12, indicating a possible nonmagnetic quadrupolar Kondo mechanism distinct from other heavy-fermion superconductors.

Findings

Isotropic or nearly isotropic energy gap indicated by temperature dependence of penetration depth

Shorter penetration depth compared to other heavy-fermion superconductors

Signature of a potentially novel nonmagnetic Kondo pairing mechanism

Abstract

Transverse-field muon spin rotation measurements in the vortex-lattice mixed state of the heavy-fermion (HF) superconductor PrOs4Sb12 yield a temperature dependence of the penetration depth indicative of an isotropic or nearly isotropic energy gap. This is not seen to date in any other HF superconductor and is a signature of isotropic pairing symmetry, possibly related to a novel nonmagnetic "quadrupolar Kondo" HF mechanism in PrOs4Sb12. The T = 0 relaxation rate \sigma_s(0) = 0.91(1) \mu s^-1 yields an estimated penetration depth \lambda(0) = 3440(20) \AA, which is considerably shorter than in other HF superconductors.