Disorder-induced first order transition and Curie temperature lowering in ferromagnetic 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 variance of the distribution of 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.