Extensions to the Kondo lattice model to achieve realistic Curie temperatures and appropriate behavior of the resistivity for manganites

TL;DR

This paper extends the two-band Kondo lattice model for manganites by including Jahn-Teller distortions and antiferromagnetic coupling, achieving realistic Curie temperatures and resistivity behavior consistent with experiments.

Contribution

It introduces extensions to the Kondo lattice model that incorporate Jahn-Teller effects and antiferromagnetic interactions, improving agreement with experimental data.

Findings

Realistic Curie temperatures achieved with intraband Coulomb repulsion.

Phase diagram shows ferromagnetic metal to paramagnetic insulator transitions.

Resistivity behavior aligns with experimental Colossal Magnetoresistance observations.

Abstract

We investigate the influence of the Jahn-Teller distortion and a direct antiferromagnetic moment coupling as extensions to a two-band Kondo lattice model for the magnetic and electronic properties of manganites. Those are calculated self-consistently via an interpolating self-energy model and a modified RKKY technique using finite Hund coupling and quantum spins. We found that both effects are essential to achieve realistic Curie temperatures if we regard intraband Coulomb repulsion. Using reliable model parameters we got results which are in very good agreement with experimental data in the whole ferromagnetic doping range. In the calculated phase diagram there are ferromagnetic metal to paramagnetic insulator transitions, accompanied by a Colossal Magnetoresistance (CMR) behavior. To improve the comparability of the measured behavior of the resistivity with the calculated one, we have to switch on interband Coulomb correlations.