NMR RELAXATION RATE IN THE HUBBARD-MODEL IN HIGH DIMENSIONS

The NMR relaxation rate in the Hubbard model in high dimensions is investigated. First, by an analysis of the response functions, it is shown that, in the infinite-dimensional models, the intersite correlation does not directly affect the local response of the system. A simple approximation to consider the effects of the finite dimensions is then presented, and effects of the antiferromagnetic (AF) correlation on the NMR relaxation rate in the finite-dimensional Hubbard model is studied by treating the interaction by the self-consistent second-order perturbation theory. It is found that at low temperatures the AF correlation seriously affects the temperature dependence of the NMR relaxation rate in contrast to the case in the infinite dimensions.