THEORY OF NMR IN HEAVY-FERMION COMPOUNDS USING THE SLAVE-BOSON TECHNIQUE

The nuclear-spin-relaxation rate, 1/T1, in several of the heavy-fermion compounds has been measured The temperature dependence of 1/T1 clearly reflects the T dependence of the f-electron susceptibility , chi-f, even though the experiments are performed on the non-f sites. A calculation is performed using the slave-boson approach to the periodic Anderson model. It is shown that the f-electron susceptibility does indeed give the observed T dependence of 1/T1 as well as that of the neutron-scattering half-width. The fact that the conduction-electron relaxation rate reflects the f-electron susceptibility can be explained by including spin fluctuations in our model. These have previously been largely ignored. We extend the calculation to the case of the noncubic Ce compounds in which anisotropy is important. We show that the anisotropy of 1/T1 does not reflect the magnetic anisotropy of the f electrons. The Knight shift is also considered. The enhancement of K2 is seen to be approximately the same as for 1/(T,T), but in this case the anisotropy of K is related to that of chi-f.