Periodic Anderson model with correlated conduction electrons

TL;DR

This paper studies a periodic Anderson model with correlated conduction electrons using dynamical mean-field theory, revealing how electron interactions influence quasiparticle formation, insulating behavior, and spectral properties.

Contribution

It introduces a detailed analysis of the periodic Anderson model with Hubbard-type conduction electron interactions, highlighting the effects on quasiparticle peaks and insulating states.

Findings

Quasiparticle peaks evolve from Hubbard model behavior at high temperatures.

System becomes an insulator with a tiny gap at low temperatures.

Increasing U_c or hybridization suppresses quasiparticle formation and enlarges the gap.

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 non-crossing 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-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.