Polaron Exchange Model for Ferromagnetic Ordering in Manganite Films

TL;DR

This paper introduces a polaron exchange model to explain ferromagnetic ordering in doped manganite films, emphasizing the role of polarons in transport and magnetic properties, supported by experimental data on Pr0.7(Sr1-xCax)0.3MnO3.

Contribution

The study develops and validates a polaron exchange model for ferromagnetic ordering in manganite films, linking polaron behavior to magnetic transition temperatures.

Findings

Polarons dominate transport in both paramagnetic and ferromagnetic states.

Curie temperature data fit well with the polaron exchange energy balance.

Polaron models effectively describe electron correlations in doped manganites.

Abstract

In doped manganites, the strong electron-phonon coupling due to the Jahn-Teller effect localizes the conduction-band electrons as polarons. This results in polarons are carriers responsible for transport and ferromagnetic ordering rather than the bare eg electrons, and sequentially polaron exchange model is emerged for describing ferromagnetic ordering. In Pr0.7(Sr1-xCax)0.3MnO3(x=0.3-0.6) epitaxial thin films, for higher-temperature paramagnetic state and lower-temperature ferromagnetic state, both the temperature dependent transports present behaviors of small polaron; for paramagnetic-ferromagnetic transition, the experimental data of Curie temperature are well described by an energy balance expression induced by polaron exchange model. These results demonstrate that the polaron models are proper ways to describe the strongly correlated electrons in the doped manganites.