Kondo screening and exhaustion in the periodic Anderson model

We investigate the paramagnetic periodic Anderson model using the dynamical mean-field theory in combination with the modified perturbation theory that interpolates between the weak and strong coupling limits. For the symmetric periodic Anderson model, the ground state is always a singlet state. However, as function of the hybridization strength, a crossover from collective to local Kondo screening is found. Reducing the number of conduction electrons, the local Kondo singlets remain stable. The unpaired f electrons dominate the physics of the system. For very low conduction electron densities, a large increase of the effective mass of the quasiparticles is visible, which is interpreted as the approach of the Mott-Hubbard transition.