Magnetic excitation in uranium compounds with 5f electrons with localized character

Metoki, Naoto   ; Yamamoto, Etsuji  ; Sakai, Hironori   ; Haga, Yoshinori   ; Matsuda, Tatsuma; Ikeda, Shugo*

US shows CEF at low temperatures, while magnetic quasi-elastic scattering with increasing temperature. The crossover of 5f character would be the origin for the unusual metal-insulator crossover. We found that the static susceptibility can be well reproduced from the Kramars-Kronnig transformation of our neutron inelastic data. It means (1) no remarkable excitation above 12 meV, (2) the local susceptibility is dominant because of the weak magnetic correlation, and (3) we can estimate the contribution to the static susceptibility from the localized and itinerant part. Localized model is a good approximation and asymptotic limit for low temperatures.