Sb-NQR study of filled skutterudite CeFe4Sb12

We report the results of 121,123Sb-nuclear quadrupole resonance (NQR) measurements on CeFe4Sb12 in order to investigate the magnetic properties at low temperatures from a microscopic viewpoint. Above 50 K, the nuclear spin-lattice relaxation time T1 shows an activated temperature dependence 1/T1∝exp(-Δ/kBT) with an energy gap Δ/kB=190K. On the other hand, below 30 K, 1/T1 is proportional to the temperature. This behavior is explained by a pseudogap model, which is suggested to be induced by the effect of the hybridization between Ce 4f and conduction electrons.