Onsager Reaction Field in Itinerant Magnetism

Abstract

Onsager reaction-field approach which corrects Weiss mean-field theory has been very successful in localized magnetism. We generalize this approach to the finite-temperature magnetism of the Hubbard model and calculate the N\'eel temperature ${T}_{N}$, the magnetic susceptibility, and the spin-spin correlation function. The results compare well with the available quantum Monte Carlo simulations.