Nature of crossover between localized and itinerant 5f states in URu2Si2 evidenced by Si29 -NMR measurement

We have carried out $^{29}\mathrm{Si}$ nuclear magnetic resonance of ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$, which undergoes the so-called hidden order (HO) at ${T}_{\mathrm{HO}}=17.5$ K. The use of a $^{29}\mathrm{Si}$-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 ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$ 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 ${T}_{\mathrm{HO}}$ by extracting magnetic fluctuation components.