Mean-field magnetic phase diagram of the periodic Anderson model with the Kondo-compensated phases

Abstract

We have determined the ground-state phase diagram for the periodic Anderson model, which comprises both metallic and insulating collinear magnetic phases with compensated magnetic moments. The compensation is due to both the almost-localized character of f moments and by an equally important Kondo-type polarization of the conduction electrons; it is effective only close to half filling. In such a situation an antiferromagnetic state with very heavy electrons is formed. Thus we introduce a true Kondo-lattice state in a self-consistent manner. The approach is based on the slave-boson method in the saddle-point approximation, in which a strong nonlinear molecular field appears in a natural way. In the polarized state the effective masses are spin dependent. At half filling the antiferromagnetic Kondo insulator evolves with increasing hybridization into a paramagnetic Kondo insulator. We also predict the existence of a weakly ferromagnetic state (with an extremely small net moment) that can be obtained from the antiferromagnetic heavy-fermion state by applying e.g., pressure.