The Kondo Lattice Model in Infinite Dimensions II. Static Susceptibilities and Phase Diagram

TL;DR

This paper investigates magnetic and charge susceptibilities in the Kondo lattice model using CT-QMC and DMFT, revealing phase transitions including antiferromagnetic, ferromagnetic, and charge-density-wave states, and comparing results with Doniach's theory.

Contribution

It provides a detailed analysis of phase transitions and susceptibilities in the Kondo lattice model, incorporating numerical methods and extending understanding beyond existing theories.

Findings

Antiferromagnetic transition near half filling at weak J

Suppression of divergence with increasing J due to Kondo effect

Observation of ferromagnetic order at low conduction electron density

Abstract

Magnetic and charge susceptibilities in the Kondo lattice are derived by the continuous-time quantum Monte Carlo (CT-QMC) method combined with the dynamical mean-field theory. For a weak exchange coupling J and near half filling of the conduction band, antiferromagnetic transition occurs as signalled by divergence of the staggered magnetic susceptibility with lowering temperature. With increasing J, the Kondo effect suppresses the divergence, and the critical value of J agrees well with Doniach's estimate which considers the RKKY interaction as competing with the Kondo effect. For low density of conduction electrons, a ferromagnetic ordering is observed where Doniach's estimate does not work. Around quarter filling, a charge-density-wave (CDW) transition is found. The CDW is interpreted from the strong-coupling limit in terms of effective repulsion between Kondo singlets.