Periodic Anderson model with correlated conduction electrons

Abstract

We investigate a periodic Anderson model with interacting conduction electrons which are described by a Hubbard-type interaction of strength ${U}_{c}.$ Within dynamical mean-field theory the total Hamiltonian is mapped onto an impurity model, which is solved by an extended noncrossing approximation. We consider the particle-hole symmetric case at half filling. Similar to the case ${U}_{c}=0,$ the low-energy behavior of the conduction electrons at high temperatures is essentially unaffected by the $f$ electrons and for small ${U}_{c}$ a quasiparticle peak corresponding to the Hubbard model evolves first. These quasiparticles screen the $f$ moments when the temperature is reduced further, and the system turns into an insulator with a tiny gap and flat bands. The formation of the quasiparticle peak is impeded by increasing either ${U}_{c}$ or the $c\ensuremath{-}f$ hybridization. Nevertheless almost dispersionless bands emerge at low temperature with an increased gap, even in the case of initially insulating host electrons. The size of the gap in the one-particle spectral density at low temperatures provides an estimate for the low-energy scale and increases as ${U}_{c}$ increases.