Zero-field μSR study of CeRu₂Si₂ heavy fermion compound

Abstract

Zero — field muon spin relaxation measurements have been carried out on a high-quality single-crystal sample of the paramagnetic heavy-fermion compound CeRu₂Si₂ from 5K to 300K. The observed relaxation at each temperature was well fitted by a function described by the product of a Kubo-Toyabe type and an exponential one. The temperature dependence of the Kubo-Toyabe relaxation rate σ_ZF shows an almost constant value (0.03 μs⁻¹) which is comparable to the calculated linewidth due to nuclear dipole fields from⁹⁹Ru and¹⁰¹Ru atoms assuming the possible μ⁺ stopping sites for the ThCr₂Si₂ structure. On the other hand, we observed an increase of the exponential relaxation rate λ_ZF to a value of ∼- 0.02 μs⁻¹ with decreasing temperature below about 100K. This suggests a contribution of Ce 4f moments.