MAGNETIC FLUCTUATIONS IN THE HEAVY-FERMION YBPDSB

Low temperature mu SR, specific heat and magnetic susceptibility measu rements are presented in a non-magnetically ordered sample of the cubi c intermetallic YbPdSb. They reveal the presence of rather slow Yb mom ent fluctuations down to 0.05 K in a heavy fermion state characterised by a very high Sommerfeld ratio of 3 J K-2 mol(-1). The relevance of these observations with respect to the formation of a spin-liquid phas e, expected in materials close to Doniach's magnetic instability for K ondo lattices, is discussed.