Enhanced magnetism of Fe3O4 nanoparticles with Ga doping

Magnetic (GaxFe1−x)3O4 nanoparticles with 5%–33% gallium doping (x = 0.05–0.33) were measured using x-ray absorption spectroscopy and x-ray magnetic circular dichroism to determine that the Ga dopant is substituting for Fe3+ as Ga3+ in the tetrahedral A-site of the spinel structure, resulting in an overall increase in the total moment of the material. Frequency-dependent alternating-current magnetic susceptibility measurements showed these particles to be weakly interacting with a reduction of the cubic anisotropy energy term with Ga concentration. The element-specific dichroism spectra show that the average Fe moment is observed to increase with Ga concentration, a result consistent with the replacement of A-site Fe by Ga.