Magnetic Phase Diagrams of Manganites-like Local-Moment Systems with Jahn-Teller distortions

TL;DR

This paper investigates the magnetic phase diagrams of manganite-like systems using an extended Kondo lattice model, incorporating Jahn-Teller distortions, Coulomb interactions, and beyond mean-field calculations to understand phase behavior.

Contribution

It introduces a comprehensive model including Jahn-Teller effects and Coulomb interactions, with self-consistent calculations beyond classical spins and mean-field approximations.

Findings

Strong influence of Coulomb interactions on phase stability

Jahn-Teller distortions significantly affect magnetic phases

Phase diagrams vary notably with Hund's coupling and antiferromagnetic exchange

Abstract

We use an extended two-band Kondo lattice model (KLM) to investigate the occurrence of different (anti-)ferromagnetic phases or phase separation depending on several model parameters. With regard to CMR-materials like the manganites we have added a Jahn-Teller term, direct antiferromagnetic coupling and Coulomb interaction to the KLM. The electronic properties are self-consistently calculated in an interpolating self-energy approach with no restriction to classical spins and going beyond mean-field treatments. Further on we do not have to limit the Hund's coupling to low or infinite values. Zero-temperature phase diagrams are presented for large parameter intervals. There are strong influences of the type of Coulomb interaction (intraband, interband) and of the important parameters (Hund's coupling, direct antiferromagnetic exchange, Jahn-Teller distortion), especially at intermediate couplings.