STUDY OF SOME FACTORS AFFECTING THERMODYNAMIC PROPERTIES OF THE INSULATING PHASE OF THE PERIODIC ANDERSON LATTICE MODEL

Within the framework of slave-boson mean-field theory, we study the th ermodynamic properties of the periodic Anderson lattice model with hal f-filled conduction band and one 4f electron at each primitive cell an d the degeneracy N-d = 2. It is found that after taking into account t he direct nearest-neighbor f-f hopping, such a periodic Anderson latti ce model can exhibit both an insulating ground state and a heavy-fermi on metal ground state depending on the value of the bare f energy leve l E-f, the hybridization matrix element V, and the direct f-f hopping strength delta. This is unlike the case neglecting the direct f-f hopp ing, in which such a periodic Anderson lattice model will predict an i nsulating ground state only.