Magnetic properties of the Hubbard model

Abstract

The magnetic interaction between localized moments is calculated using the functional integral scheme in the static and saddle-point approximation. The interaction is shown to reduce to the usual RKKY expression in the low-U case and to the Anderson (1959) superexchange in the small- bandwidth limit. The asymptotic behaviour of the interaction, when the distance between the moments is very large, changes from RKKY's one to damped RKKY when U is increased.