Heavy Quasiparticles in the Anderson Lattice Model

An exact-diagonalization technique on small clusters is used to study the dynamics of the one-dimensional symmetric Anderson lattice model. Our calculated excitation spectra reproduce key features expected for an infinite Kondo lattice such as nearly localized low-energy spin excitations and extended regions of ``heavy-quasiparticle'' bands. We show that, in contrast to the hybridization picture, low-energy spin excitations of the nearly localized f-electron system play a key role in the formation of an almost dispersionless low-energy band of heavy quasiparticles.