Antiferromagnetic heavy-fermion and Kondo-insulating states with compensated magnetic moments

Abstract

We discuss the magnetic phases in the periodic Anderson model and determine the conditions under which there appears a stable Fermi-liquid state with (i) small antiferromagnetic moment of $f$ electrons, largely compensated by the conduction electrons, (ii) high density of states at the Fermi level, and (iii) almost integer occupation of the $f$ level. We use a modified version of the spin rotationally invariant slave-boson approach, in which a strong nonlinear molecular field acting on $f$ electrons appears already in the saddle-point approximation. For an even number of electrons an antiferromagnetic Kondo insulating state transforms with increasing hybridization into a paramagnetic Kondo insulator.