Unusual magnetic behavior in ferrite hollow nanospheres

TL;DR

This paper investigates the unique magnetic properties of iron oxide hollow nanospheres, revealing complex magnetic phases due to surface effects and atomic disorder in these nanoscale structures.

Contribution

It introduces the observation of unusual magnetic behavior in ferrite hollow nanospheres and explains it through coexistence of superparamagnetic and cluster-glass phases.

Findings

Presence of a soft superparamagnetic phase.

Existence of a hard, cluster-glass like phase.

High magnetic disorder due to surface atoms.

Abstract

We report unusual magnetic behavior in iron oxide hollow nanospheres of 9.3 $nm$ in diameter. The large fraction of atoms existing at the inner and outer surfaces gives rise to a high magnetic disorder. The overall magnetic behavior can be explained considering the coexistence of a soft superparamagnetic phase and a hard phase corresponding to the highly frustrated cluster-glass like phase at the surface regions.