GROUND-STATE AND MAGNETIC-SUSCEPTIBILITY OF INTERMEDIATE-VALENCE TM IMPURITIES

We consider the appropriate generalization of the Anderson model for a Tm impurity in a cubic crystal field. In the 4f(12) configuration we include only the two multiplets of lowest energy: a singlet Gamma(1) and a triplet Gamma(4). Similarly we include only the doublet ground state of the 4f(13) configuration, and (to make our numerical method feasible) we assume that the conduction-electron partial waves with symmetry Gamma(8) can be neglected. We study the model using Wilson's renormalization group. The resulting ground state is a singlet or a doublet depending mainly on the relative strength of the hybridization of the 4f(13) doublet with both 4f(12) states. A doublet ground state is consistent with the experimental evidence.