NMR Study of Uranium Ternary Compounds with a Weak Magnetic Interaction

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In order to investigate interesting physical phenomena such as the Kondo effect and heavy fermion behavior for uranium ternary compounds, we have searched the uranium ternary compounds with a weak magnetic interaction and have studied them microscopically with NMR.Prof.Takabatake, and investigator, has synthesized new U-T-Ga compounds (T=Ni, Cu and Pd). In these compounds UCu_<3+x>Ga_<2-x> (0.1*x*0.8) shows a maximum T_N(x) near x=0.3 and a nonmagnetic heavy-fermion state with further increase in x.Prof.Kojima, the head investigator, has performed NMR measurement for UPt_2Sn and U_3Pt_3Sn_4. The ^<119>Sn NMR is observable down to 4.2 K in spite of disappearance of the ^<195>Pt NMR below T_N=60K.This suggests a spin structure which results in a cancellation of the transferred hyperfine fields at a Sn site. ^<195>Pt and ^<119>Sn Knight shifts in U_3Pt_3Sn_4 have been measured down to 4.2 K and temperature variations of the Knight shift saturate near 4.2 K.This results suggest that the 5f electron state is delocalized in this temperature range.