The Kondo lattice model with correlated conduction electrons

TL;DR

This paper explores a Kondo lattice model with correlated conduction electrons using dynamical mean-field theory, revealing how electron correlations influence quasiparticle formation and lead to an insulating state at low temperatures.

Contribution

It establishes a connection between the Kondo lattice and Anderson-Hubbard models within dynamical mean-field theory and extends numerical methods to study correlated conduction electrons.

Findings

Quasiparticles form at higher temperatures unaffected by the lattice.

The system becomes insulating at lower temperatures with a gap opening.

Stronger correlations increase the insulating gap.

Abstract

We investigate a Kondo lattice model with correlated conduction electrons. Within dynamical mean-field theory the model maps onto an impurity model where the host has to be determined self-consistently. This impurity model can be derived from an Anderson-Hubbard model both by equating the low-energy excitations of the impurity and by a canonical transformation. On the level of dynamical mean-field theory this establishes the connection of the two lattice models. The impurity model is studied numerically by an extension of the non-crossing approximation to a two-orbital impurity. We find that with decreasing temperature the conduction electrons first form quasiparticles unaffected by the presence of the lattice of localized spins. Then, reducing the temperature further, the particle-hole symmetric model turns into an insulator. The quasiparticle peak in the one-particle spectral density splits and a gap opens. The size of the gap increases when the correlations of the conduction electrons become stronger. These findings are similar to the behavior of the Anderson-Hubbard model within dynamical mean-field theory and are obtained with much less numerical effort.