Finite-temperature slave-boson description of the ferromagnetic instabilities of the Anderson lattice

Using the Kotliar and Ruckenstein slave-boson formalism we consider the finite-U Anderson lattice. We study the appearance of ferromagnetic instabilities and their stabilities. We study both the groundstate and the finite temperature regimes as a function of the Coulomb repulsion, density and f-level location. In the insulating regime there is a ferromagnetic phase that competes with the paramagnetic phase. In the metallic regime there are two ferromagnetic phases as the coupling grows. We calculate the critical temperatures as a function of coupling.