R. Allub et Aa. Aligia, GROUND-STATE AND MAGNETIC-SUSCEPTIBILITY OF INTERMEDIATE-VALENCE TM IMPURITIES, Physical review. B, Condensed matter, 52(11), 1995, pp. 7987-7993
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) a
nd a triplet Gamma(4). Similarly we include only the doublet ground st
ate of the 4f(13) configuration, and (to make our numerical method fea
sible) we assume that the conduction-electron partial waves with symme
try Gamma(8) can be neglected. We study the model using Wilson's renor
malization 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 con
sistent with the experimental evidence.