Mixed-phase description of colossal magnetoresistive manganites

TL;DR

This paper presents a refined mixed-phase model for colossal magnetoresistive manganites, capturing the coexistence of metallic and insulating regions and explaining their phase behavior and magnetoresistance.

Contribution

It introduces a self-consistent mixed-phase description based on competing components, aligning well with experimental phase diagrams and resistivity data.

Findings

Phase diagram matches experimental data

Negative magnetoresistance observed near Curie temperature

Model explains coexistence of conducting and insulating regions

Abstract

In view of recent experiments, indicating the spatial coexistence of conducting and insulating regions in the ferromagnetic metallic phase of doped manganites, we propose a refined mixed-phase description. The model is based on the competition of a double-exchange driven metallic component and a polaronic insulating component, whose volume fractions and carrier concentrations are determined self-consistently by requiring equal pressure and chemical potential. The resulting phase diagram as well as the order of the phase transition are in very good agreement with measured data. In addition, modelling the resistivity of the mixed, percolative phase by a random resistor network, we obtain a pronounced negative magnetoresistance in the vicinity of the Curie temperature $T_C$.