Nuclear magnetic resonance study of the heavy-fermion system URu 2Si 2

Abstract

Nuclear magnetic resonance (NMR) and relaxation studies on 29Si have been carried out on the heavy Fermion system URu 2Si 2. Above the Kondo temperature of about 60 K, the nuclear relaxation time T 1 is nearly temperature independent, which is consistent with the occurrence of fluctuations of localized U moments. Below about 60 K T 1 is inversely proportional to temperature suggesting that the system behaves like a Fermi liquid. A sharp increase in T 1 occurs below 17 K which is probably associated with the opening of an energy gap at the Fermi surface due to the formation of a spin density wave state. Below about 10 K, T 1 reacquires the inverse temperature dependence observed in the 17 K ∼ 60 K temperature range.