Interactions and magnetic relaxation in boron doped Mn3O4 nanoparticles

Abstract

We have studied magnetic interactions in phase pure Mn3O4 and composite Mn2O3/Mn3O4 nanoparticle systems having different interparticle separations between the Mn3O4 ferrimagnetic cores. We characterized the morphology and structure of these nanoparticles using x-ray diffraction and transmission electron microscopy. We find that the incorporation of boron stabilizes the Mn3O4 spinel structure resulting in the formation of phase pure nanoparticles, while in the absence of boron, the sample consists of both Mn3O4 and antiferromagnetic Mn2O3 nanoparticles. We correlate the morphology of these systems with their magnetic properties using ac susceptibility studies. The low temperature frequency dependent relaxation exhibits larger magnetic interactions in the phase pure Mn3O4 nanoparticles as compared to the Mn3O4/Mn2O3 composites, which we attribute to differences in the separation between the ferrimagnetic cores in these two samples.