Interaction of a magnetic impurity with strongly correlated conduction electrons.

Abstract

We consider a magnetic impurity which interacts by hybridization with a system of strongly correlated conduction electrons. The latter are described by a Hubbard Hamiltonian. The charge degrees of freedom of the magnetic impurity are eliminated by means of a canonical transformation, which reduces to the Schrieffer-Wolff transformation in the case of uncorrelated conduction electrons. In the limit of strong correlations, the coefficient of the dominant exchange coupling of the magnetic impurity with the nearest lattice site is modified. When the system is hole doped, there is also an antiferromagnetic coupling to the nearest neighbors of that site involving, additionally, a hole. Furthermore, it is found that the magnetic impurity attracts a hole. In the case of electron doping, double occupancies are repelled by the impurity. In contrast to the hole-doped case, we find no magnetic coupling that additionally involves a doubly occupied site.