Low energy excitations of the Anderson lattice model

Effects of a magnetic field on the single electron excitation spectrum and the distribution function of electrons are studied in the Anderson lattice model, which consists of a conduction band hybridizing with non-degenerate correlated electrons, by using the exact diagonalization technique on small clusters, We find that in the so-called Kondo insulator, the excitation gap in the spectrum remains open unless the f electrons are almost fully polarized, in contrast with the hybridization picture.