Disorder-Induced First Order Transition and Curie Temperature Lowering in Ferromagnatic Manganites

TL;DR

This paper investigates how size disorder in cations affects the magnetic phase transition and Curie temperature in manganites, revealing that disorder can lower the transition temperature and change the transition order.

Contribution

It introduces a theoretical model linking cation size disorder to magnetic properties, explaining the transition from second to first order in manganites.

Findings

Curie temperature decreases linearly with disorder variance

Transition becomes first order at high disorder levels

Provides a framework for understanding disorder effects in manganites

Abstract

We study the effect that size disorder in the cations surrounding manganese ions has on the magnetic properties of manganites. This disorder is mimic with a proper distribution of spatially disordered Manganese energies. Both, the Curie temperature and the order of the transition are strongly affected by disorder. For moderate disorder the Curie temperature decreases linearly with the the variance of the distribution of the manganese site energies, and for a disorder comparable to that present in real materials the transition becomes first order. Our results provide a theoretical framework to understand disorder effects on the magnetic behavior of manganites.