Magnetic correlations in Kondo lattice problem

Encouraged by the recent developments in the t-J model of high-Tc problem we try to make connections to the Kondo lattice problem with special attention to its ground-state magnetic properties. Starting from the periodic Anderson Hamiltonian we integrate out the conduction-electron Grassmann variables and obtain an effective action for the f-level electrons, which is similar to the Hubbard model except that the hopping amplitude (t) is long-ranged, sinusoidal in space and retarded in time. Close to the Kondo limit in the lattice case the mean occupation number of f-level electrons is close to one, corresponding to low doping limit. Some lessons can be borrowed from the t-J model. Mainly the special feature of t makes the Kondo problem much more difficult. (orig.)