Nature Of Crossover Between Localized And Itinerant 5 F States In Uru2si2 Evidenced By Si-29-Nmr Measurement

We have carried out Si-29 nuclear magnetic resonance of URu2Si2, which undergoes the so-called hidden order (HO) at T-HO = 17.5 K. The use of a Si-29-enriched sample enabled us to obtain accurate NMR data up to 350 K and to extract the features of low energy magnetic correlations at high temperatures in this compound. Present results naturally indicate that URu2Si2 undergoes a crossover from localized to itinerant regimes with decreasing temperature and the HO occurs in the crossover region. We also discuss possible antiferromagnetic correlations remaining down to THO by extracting magnetic fluctuation components.