ZERO-FIELD MU-SR STUDY OF CERU2SI2 HEAVY-FERMION COMPOUND

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 sigma(ZF) shows an almost constant value (0.03 mus-1) which is comparable to the calculated linewidth due to nuclear dipole fields from Ru-99 and Ru-101) atoms assuming the possible mu+ stopping sites for the ThCr2Si2 structure. On the other hand, we observed an increase of the exponential relaxation rate lambda(ZF) to a value of congruent-to 0.02 mus-1 with decreasing temperature below about 100K. This suggests a contribution of Ce 4f moments.