Phase Separation in Electronic Models for Manganites

TL;DR

This paper investigates phase separation phenomena in manganites using a Kondo lattice model, revealing a regime where antiferromagnetic and ferromagnetic regions coexist, with results aligning with experimental observations.

Contribution

It introduces a detailed analysis of phase separation in manganites via the Kondo lattice Hamiltonian, highlighting a novel regime with mixed magnetic phases.

Findings

Identification of phase separation between antiferromagnetic and ferromagnetic regions.

Incommensurate spin correlations observed.

Estimated critical temperature matches experimental data.

Abstract

The Kondo lattice Hamiltonian with ferromagnetic Hund's coupling as a model for manganites is investigated. The classical limit for the spin of the (localized) $t_{2g}$ electrons is analyzed on lattices of dimension 1,2,3 and $\infty$ using several numerical methods. The phase diagram at low temperature is presented. A regime is identified where phase separation occurs between hole undoped antiferromagnetic and hole-rich ferromagnetic regions. Experimental consequences of this novel regime are discussed. Regions of incommensurate spin correlations have also been found. Estimations of the critical temperature in 3D are compatible with experiments.