MAGNETIC IMPURITY IN THE ONE-DIMENSIONAL HUBBARD-MODEL

The Hubbard chain with a magnetic impurity of arbitrary spin S is stud ied using the Bethe ansatz technique. We consider two kinds of impurit ies which interact with itinerant electrons on the neighboring lattice sites without destroying the integrability. The correlations in the h ost always induce valence fluctuations at the impurity site. For a rep ulsive Hubbard U, an impurity coupled via antiferromagnetic exchange t o the host reveals magnetic properties similar to those of the ordinar y Kondo effect. In contrast, a hybridization impurity (Anderson-like) embedded into the attractive Hubbard model gives rise to essentially d ifferent magnetic behavior. This difference is a consequence of the sp in gap in the host.