Muon spin rotation and relaxation studies of the filled skutterudite superconductor ThPt4Ge12.

Longitudinal and transverse field muon spin rotation/relaxation measurements have been carried out on a polycrystalline sample of ThPt(4)Ge(12). The zero-field measurements in the longitudinal geometry do not reveal any signature of a spontaneous internal magnetic field below the superconducting transition temperature, indicating the preservation of time-reversal symmetry in the superconducting state of ThPt(4)Ge(12). From the transverse field data, the zero field magnetic penetration depth, λ(0), was estimated to be 110(15) nm, and then we have estimated the effective mass of the quasiparticles, m*≈4.5m(e), and the superfluid carrier density, n(s)≈1.06 × 10(28) carriers m(-3). We found a marked difference between the zero-field cooling and field-cooled vortex state muon spin relaxation rates, σ(s)(T), below the irreversibility temperature, T(ir) ∼ 2.5 K. A linear field dependence of σ(s)(H) and power law behaviour of σ(s)(T) exhibit a significant deviation from those expected for isotropic BCS-superconductors. The analysis of correlation between the superconducting transition temperature and the effective Fermi temperature within the Uemura classification scheme reveals that the condensation energy in ThPt(4)Ge(12) is comparable to those of exotic superconductors.