Direct Observation of High-Temperature Polaronic Behavior In Colossal Magnetoresistive Manganites

TL;DR

This study reveals how the electronic and atomic structures of colossal magnetoresistive manganites change dramatically at the Curie temperature, highlighting polaron formation and phase separation phenomena.

Contribution

It provides direct experimental evidence of high-temperature polaronic behavior and phase separation in manganites using advanced spectroscopic techniques.

Findings

Charge localization and increased Mn spin moments at Curie temperature

Observation of Jahn-Teller distortions indicating polaron formation

Evidence supporting phase-separation scenario in manganites

Abstract

The temperature dependence of the electronic and atomic structure of the colossal magnetoresistive oxides $La_{1-x}Sr_{x}MnO_{3}$ (x = 0.3, 0.4) has been studied using core and valence level photoemission, x-ray absorption and emission, and extended x-ray absorption fine structure spectroscopy. A dramatic and reversible change of the electronic structure is observed on crossing the Curie temperature, including charge localization and spin moment increase of Mn, together with Jahn-Teller distortions, both signatures of polaron formation. Our data are also consistent with a phase-separation scenario.