NMR Study of Uranium Ternary Compounds with a Weak Magnetic Interaction

为了研究铀三元化合物的Kondo效应和重费米子行为等有趣的物理现象，我们寻找了具有弱磁相互作用的铀三元化合物，并用NMR对其进行了微观研究。研究者Takabatake教授合成了新的U-T-Ga化合物（T=Ni，Cu和Pd）。UCu_（3+x）Ga_<2-x>（0.1*x*0.8）在x=0.3附近具有最大的T_N（x），随着x的进一步增大，出现一个重费米子态。Kojima教授对UPt_2Sn和U_3Pt_3Sn_4进行了NMR测量。在<119><195>T_N= 60 K以下，~ 1 Pt NMR消失，但~ 1 Sn NMR在4.2 K以下仍能观测到，这表明Sn位上的自旋结构导致了转移超精细场的抵消.测量<195><119>了U_3Pt_3Sn_4中的^ Pt和^ Sn的Knight位移，在4.2K附近Knight位移的温度变化达到饱和，表明5 f电子态在此温度范围内是离域的。

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.