Competition between Coqblin-Schrieffer and local exchange interactions in Kondo systems by the perturbative renormalization group

A model which accounts for the competition between hybridization and local exchange (LE) interactions in anomalous Ce systems is proposed. In this mod el a localized magnetic moment j(f)=5/2 has an antiferromagnetic Coqblin-Sc hrieffer (CS) coupling with l=3 conduction electrons partial waves, due to hybridization, and a contact coupling with l=0 partial waves due to the LE interaction. The last term breaks the SU(N) symmetry of the CS model. Using the perturbative renormalization group, we show that the SU(N) ground stat e of the CS model remains the ground state even in the presence of a LE int eraction stronger than the CS coupling. We discuss the effect of the LE on the Kondo temperature. Moreover, when the LE coupling reaches a critical va lue the system has a non-Fermi-liquid non-SU(N) ground state, and when it i s stronger than the critical value the system falls into an undercompensate d Kondo state. [S0163-1829(99)00210-6].