Correlation effect of the doped Kondo insulator described on the basis of the periodic Anderson model

We study the periodic Anderson model away from half filling in the framework of self-consistent second-order perturbation theory. The carrier concentration dependence of the density of states spectrum, spin and charge susceptibilities, and magnetization process is systematically investigated. We find that the coefficient gamma of the linear-in-T specific heat and the spin susceptibility chi (s)(T) at T=0 decrease as the carrier concentration decreases near half filling, while gamma and chi (s)(T=0) themselves are strongly enhanced by the Coulomb interaction. In the temperature dependence of the spin susceptibility and the magnetic-field dependence of the magnetization, it is found that the characteristic energy that corresponds to the hybridization gap appearing at half filling is observed even away from half filling, and another characteristic energy appears in the system with finite doping. Although there are apparently two distinguishable energy scales away from half filling, it is shown that they are related by the Fermi liquid parameter and both are nothing but energy scales that characterize quasiparticles constructed in the renormalized hybridization band.