MAGNETIC IMPURITY IN A SYSTEM OF CORRELATED ELECTRONS

We consider a magnetic ion embedded in a system of correlated conducti on electrons and study the effect of correlations on the Kondo energy scale. The conduction electrons are described by a Hubbard Hamiltonian . For weakly correlated conduction electrons the Kondo energy increase s (decreases) exponentially as a function of a repulsive (attractive) Hubbard interaction U. In the limit of large U where the Hubbard Hamil tonian reduces to that of the t-J model, the spin degrees of freedom a re described by a mean-held slave boson approach. The impurity spin is assumed to be situated in a uniform spin Liquid resonating valence bo nd state. Modifications in the Kondo scale due to spinon interactions are pointed out.