Surface phase separation in nanosized charge-ordered manganites

TL;DR

This paper proposes a phenomenological model explaining how surface phase separation induces ferromagnetism in nanosized charge-ordered manganites, accounting for experimental observations of weakened charge-ordering and emergent ferromagnetism.

Contribution

It introduces a surface phase separation model that explains ferromagnetism in nanoscale manganites, linking surface effects to magnetic property changes.

Findings

Formation of a ferromagnetic shell increases as grain size decreases

Predicted exchange bias effects in nanosized manganites

Softening of the ferromagnetic transition due to surface effects

Abstract

Recent experiments showed that the robust charge-ordering in manganites can be weakened by reducing the grain size down to nanoscale. Weak ferromagnetism was evidenced in both nanoparticles and nanowires of charge-ordered manganites. To explain these observations, a phenomenological model based on surface phase separation is proposed. The relaxation of superexchange interaction on the surface layer allows formation of a ferromagnetic shell, whose thickness increases with decreasing grain size. Possible exchange bias and softening of the ferromagnetic transition in nanosized charge-ordered manganites are predicted.