Aspects of the FM Kondo Model: From Unbiased MC Simulations to Back-of-an-Envelope Explanations

TL;DR

This paper derives simplified effective models from the ferromagnetic Kondo lattice model with classical corespins, demonstrating their ability to predict key magnetic properties and offering explanations for phenomena like particle density jumps.

Contribution

It introduces effective models that reduce computational effort and provides new insights into the origin of particle density jumps in the model.

Findings

Double exchange accurately predicts Curie temperature magnitude and doping dependence.

Particle density jumps are explained by ferromagnetic polarons, not phase separation.

Effective models align well with unbiased Monte Carlo simulation results.

Abstract

Effective models are derived from the ferromagnetic Kondo lattice model with classical corespins, which greatly reduce the numerical effort. Results for these models are presented. They indicate that double exchange gives the correct order of magnitude and the correct doping dependence of the Curie temperature. Furthermore, we find that the jump in the particle density previously interpreted as phase separation is rather explained by ferromagnetic polarons.